Kygo Health

9 MODELS · 4 BRANDS · OFFICIAL SPECS ONLY

Which smart ring should you buy?

Four brands, 9 current models, and no single winner. Tell the finder what you actually care about, from cost to battery to whether anyone independent has checked the accuracy, and it ranks every ring against that. Then compare the specs, the software and the real multi-year cost, model by model.

9

Current models compared

$199

Cheapest 3-year total

15

d

Longest rated battery

1

/4

Brands with independent validation

The quick answer

Four brands, four different bets.

The full interactive comparison is below. If you just want the verdict, start here.

Every ring here reads the same finger with the same basic optical sensor. What separates them is the business model, the evidence, and in two cases whether you can legally buy one.

Oura

The longest feature list, and the only independent validation.

$399 for the Ring 5 or $349 for the Ring 4, plus $69.99/yr. You are renting the software, and it is the best-evidenced software here.

RingConn

The most published capability per dollar.

$349 flat for the Gen 3, or $199 for the Gen 2 Air. No subscription on any model, 14-day battery, case in the box, and sleep apnea monitoring nobody else lists.

Ultrahuman

The widest ecosystem, the thinnest evidence base.

$479 for the Ring PRO: 15 rated days, plus a first-party CGM and blood-panel stack. It is still a US pre-order, the Ring AIR is barred from the US, and no independent study has tested either.

CUDIS

The least published information of the four.

$349 or $399, no subscription, and a battery two testers beat the claim on. No engineering spec and no accuracy figure. Has a skin temperature sensor. No engineering spec and no accuracy figure. Absent data is not proof it is inaccurate, just that nobody has published either way.

So which should you buy?

No ring here wins on every axis, so pick the trade-off you prefer.

Gen 3 for the most published capability with nothing recurring, at the cost of a smaller software list. Oura for accuracy someone outside the company has checked and the deepest app, at roughly $250 more over three years. Ring PRO for the longest battery and a CGM and blood-panel stack, if you can wait out the US pre-order. CUDIS or the $199 Gen 2 Air for the lowest price, accepting that CUDIS publishes no specs or accuracy figures.

Free 7-Day Trial

Your ring shows the number. Kygo shows why.

Any ring here can tell you your HRV dropped. None can tell you why. Kygo links your ring data to what you ate and how you trained, so you can see what actually moved it.

Works with

Oura

Apple

Fitbit

Garmin

WHOOP

Polar

Google

Health

Ring finder

Tell us what matters. We will rank the rings.

Switch on the things you actually care about. Every model is scored 0 to 100 on each one and re-ranked live. Pick nothing and you get the all-round ranking, every priority weighted equally.

What matters most to you?

Pick one

Lowest total cost

No subscription

Longest battery

Deepest feature set

Independent validation

Sleep apnea monitoring

Women's health

Buyable in the US today

Pick one priority above to rank all 9. One at a time, so you see the real figure rather than a blended score.

All 9 models, priced low to high. No ranking applied.

RingConn Gen 2 Air

$199

Amazon

RingConn Gen 2

$299

Amazon

Oura Ring 4

$349 + sub

Amazon

RingConn Gen 3

$349

Amazon

Ultrahuman Ring AIR

$349

ultrahuman.com

CUDIS 002 Classic

$349

cudis.xyz

Oura Ring 5

$399 + sub

Amazon

CUDIS 002 Sporty

$399

cudis.xyz

Ultrahuman Ring PRO

$479

ultrahuman.com

Cost, subscription, battery and feature count are read straight from the tables below, so they can never disagree with them. Feature count is how many of the 50 tracked features a brand publishes, which measures how much it claims, not how well it works. Independent validation counts only peer-reviewed work the brand did not run itself. One priority at a time, on purpose: these eight are not the same kind of thing, so blending them would invent a winner rather than find one.

Side by side

Ranked by lowest total cost ·

Reset

Best match

Ranked by longest battery ·

Ranked by independent validation ·

Ranked by women's health ·

Oura Ring 4

Oura

Multiple peer-reviewed studies

The cheapest way into the Oura app and the same software as the Ring 5, including the metabolic suite and Natural Cycles pairing. Membership still applies.

$349 + sub

View on Amazon

#2

Cycle Insights + Natural Cycles

Ultrahuman Ring PRO

Ultrahuman

15 days rated

The longest rated battery here (15 days, up to 45 with the case) and the widest first-party ecosystem: CGM, blood panels, a home sleep monitor. It is still a US pre-order.

$479

View on ultrahuman.com

#2

In-house only, largest n=6

The rest of the field

#4

Oura Ring 5

Multiple peer-reviewed studies

#5

RingConn Gen 2

One feasibility study, n=230

#6

RingConn Gen 3

One feasibility study, n=230

#7

Ultrahuman Ring AIR

In-house only, largest n=6

#8

CUDIS 002 Classic

None published

#9

CUDIS 002 Sporty

None published

Cost, subscription, battery and feature count are read straight from the tables below, so they can never disagree with them. Feature count is how many of the 50 tracked features a brand publishes, which measures how much it claims, not how well it works. Independent validation counts only peer-reviewed work the brand did not run itself. One priority at a time, on purpose: these eight are not the same kind of thing, so blending them would invent a winner rather than find one.

Side by side

Free plug + paid Pro tier

#3

RingConn Gen 3

RingConn

14 days rated

Everything unlocked at purchase, 14-day rated battery, the charging case in the box, plus sleep apnea pattern monitoring and nighttime vascular trends.

$349

View on Amazon

#3

RingConn Gen 2

RingConn

12 days rated

Apnea pattern monitoring, SpO2, HRV and cycle tracking at $299 with no subscription. The thinnest wall here at 2.0 mm.

$299

View on Amazon

The rest of the field

#4

RingConn Gen 2 Air

10 days rated

#5

CUDIS 002 Classic

10 days rated

#6

CUDIS 002 Sporty

10 days rated

#7

Oura Ring 5

9 days rated

#8

Oura Ring 4

8 days rated

#9

Ultrahuman Ring AIR

6 days rated

Cost, subscription, battery and feature count are read straight from the tables below, so they can never disagree with them. Feature count is how many of the 50 tracked features a brand publishes, which measures how much it claims, not how well it works. Independent validation counts only peer-reviewed work the brand did not run itself. One priority at a time, on purpose: these eight are not the same kind of thing, so blending them would invent a winner rather than find one.

Side by side

RingConn Gen 2 Air

RingConn

$199 over 3 years

The lowest-cost ring in this comparison at $199 flat. It drops apnea monitoring and swaps titanium for stainless steel, but keeps the core sensing.

$199

View on Amazon

The rest of the field

#2

RingConn Gen 2

$299 over 3 years

#3

RingConn Gen 3

$349 over 3 years

#4

Ultrahuman Ring AIR

$349 over 3 years

#5

CUDIS 002 Classic

$349 over 3 years

#6

CUDIS 002 Sporty

$399 over 3 years

#7

Ultrahuman Ring PRO

$479 over 3 years

#8

Oura Ring 4

$553 over 3 years

#9

Oura Ring 5

$603 over 3 years

Cost, subscription, battery and feature count are read straight from the tables below, so they can never disagree with them. Feature count is how many of the 50 tracked features a brand publishes, which measures how much it claims, not how well it works. Independent validation counts only peer-reviewed work the brand did not run itself. One priority at a time, on purpose: these eight are not the same kind of thing, so blending them would invent a winner rather than find one.

Side by side

One feasibility study, n=230

Full cycle + monthly report

Cycle Insights + Natural Cycles

Free plug + paid Pro tier

Full cycle + monthly report

Full cycle + monthly report

Cycle tracking, temperature-based

Cycle tracking, temperature-based

Every spec, model by model.

Pick up to four models, then switch categories. Six categories across all 9 models, including a validation tab most comparison charts leave out. Official manufacturer figures only, and "not published" means exactly that.

Compare

4 of 4 selected

Oura Ring 5

$399

Oura Ring 4

$349

RingConn Gen 3

$349

RingConn Gen 2

$299

RingConn Gen 2 Air

$199

Ultrahuman Ring PRO

$479

Ultrahuman Ring AIR

$349

CUDIS 002 Classic

$349

CUDIS 002 Sporty

$399

Overview

9

Hardware

10

Battery

5

Cost

6

Validation

5

Warranty

5

Oura Ring 5 on AmazonRingConn Gen 3 on AmazonUltrahuman Ring PRO on ultrahuman.comCUDIS 002 Classic on cudis.xyz

Note: Ultrahuman also lists a Diesel edition and an $1,799 Ring Rare, both blocked from US sale, and Oura sells a Ring 4 Ceramic at $399. CUDIS Ring 001 is discontinued. Prices verified September 2, 2026; regional pricing and promotions vary.

Feature by feature

3 of 4 selected

RingConn Gen 3 on AmazonUltrahuman Ring PRO on ultrahuman.comCUDIS 002 Classic on cudis.xyz

Oura Ring 4 on AmazonRingConn Gen 3 on AmazonUltrahuman Ring PRO on ultrahuman.comCUDIS 002 Classic on cudis.xyz

Oura Ring 4 on AmazonUltrahuman Ring PRO on ultrahuman.comCUDIS 002 Classic on cudis.xyz

Oura Ring 4 on AmazonRingConn Gen 2 on AmazonUltrahuman Ring PRO on ultrahuman.comCUDIS 002 Classic on cudis.xyz

Oura Ring 4 on AmazonRingConn Gen 2 on AmazonCUDIS 002 Classic on cudis.xyz

Oura Ring 4 on AmazonRingConn Gen 2 on AmazonUltrahuman Ring AIR on ultrahuman.comCUDIS 002 Classic on cudis.xyz

Oura Ring 4 on AmazonRingConn Gen 2 on AmazonUltrahuman Ring AIR on ultrahuman.com

Oura Ring 4 on AmazonRingConn Gen 2 on AmazonUltrahuman Ring AIR on ultrahuman.comCUDIS 002 Sporty on cudis.xyz

Note: CUDIS publishes no engineering specification on any first-party surface, so band width, thickness, battery capacity, Bluetooth version and on-ring storage are genuinely absent rather than unknown. Ultrahuman publishes two conflicting Ring AIR figures: its Technical Specifications give 2.45 to 2.8 mm and 2.4 to 3.6 g varying by size, while its own comparison table says a flat 2.4 mm and 2.4 g. The ranges are used here.

Feature by feature

Note: every battery figure is a manufacturer rating under that company's own test conditions and none are cross-comparable. RingConn's apnea monitoring increases draw, so the Gen 3 rates 10 to 12 days with vibration on. CUDIS is the one claim here that independently over-delivers: two testers reached roughly two weeks.

Feature by feature

Note: Oura totals assume a continuous $69.99/yr membership with the first month free, which is why three years lands at ~$603 and not $609. It is cancelable at any time and you keep the three daily scores. Ultrahuman's PowerPlug figure is the $133/yr all-in value Ultrahuman itself publishes on the Ring Rare page; most buyers will pay nothing or $24 to $39 a year for one plug.

Feature by feature

Note: "None found" means a search of the peer-reviewed literature and each company's own science pages returned nothing, not that a study exists and we missed it. A PubMed query for "Ultrahuman ring" returns zero results, and Dial 2025, the five-device ring head-to-head against a Polar H10 ECG, tested neither Ultrahuman nor CUDIS. openFDA returned zero 510(k) and zero establishment records for CUDIS against controls that did return results.

Feature by feature

Note: Ultrahuman's warranty is valid only in the country of purchase, with no international coverage, and UltrahumanX is explicitly "backed by Ultrahuman, not by an insurer" with all benefits discretionary and no financial reimbursement. The Ring PRO is not named anywhere in Ultrahuman's Terms of Sale, so its return window is undocumented.

Feature by feature

What each app actually tracks.

A brand-level look at the software across 50 features. Oura's column assumes an active membership; without it everything collapses to the three daily scores. Ultrahuman's assumes the Ring PRO. A dash means the feature is absent from that brand's official pages, not proof it never exists in-app.

Daily scores

8

Sleep

6

Heart

7

Activity & stress

8

Women's health

6

Metabolic

5

AI & data

10

Cost calculator

What you'll actually spend.

Oura's membership ($69.99/yr) is required for almost every insight beyond the three daily scores. Ultrahuman's PowerPlugs are optional but real, valued at $133/yr on Ultrahuman's own page. RingConn and CUDIS charge nothing. Pick any two models and a horizon.

Compare two rings

Oura Ring 5

$399 + sub

Oura Ring 4

$349 + sub

RingConn Gen 3

$349

RingConn Gen 2

$299

RingConn Gen 2 Air

$199

Ultrahuman Ring PRO

$479

Ultrahuman Ring AIR

$349

CUDIS 002 Classic

$349

CUDIS 002 Sporty

$399

Time horizon

3 years

Oura Membership is $5.99/mo or $69.99/yr, first month free for new members, and is required for trends, HRV detail, the metabolic suite and most insights. RingConn and CUDIS require nothing. Ultrahuman charges nothing for ring data; AFib detection and ovulation confirmation are paid PowerPlugs. Hardware and Oura membership are HSA/FSA eligible.

Ultrahuman add-ons

Add every PowerPlug ($133/yr, Ultrahuman's own valuation)

3-year total cost of ownership

Oura Ring 5

Membership required

$603

$399 hardware + 3 × $69.99/yr membership (first month free)

RingConn Gen 3

No subscription

$349

$349 hardware + $0 required subscription

Oura Ring 5 costs $254 more than RingConn Gen 3 over 3 years. About $204 of that is membership, which is what funds the deeper feature set and the validation program. Cost is one input, and the cheaper option is not automatically the better buy: check what each side actually publishes in the feature and validation tables above before letting the dollar gap decide.

Quick winner

Oura Ring 4

$553

$349 hardware + 3 × $69.99/yr membership (first month free)

Oura Ring 4 costs $204 more than RingConn Gen 3 over 3 years. About $204 of that is membership, which is what funds the deeper feature set and the validation program. Cost is one input, and the cheaper option is not automatically the better buy: check what each side actually publishes in the feature and validation tables above before letting the dollar gap decide.

RingConn Gen 2

$299

$299 hardware + $0 required subscription

Oura Ring 4 costs $254 more than RingConn Gen 2 over 3 years. About $204 of that is membership, which is what funds the deeper feature set and the validation program. Cost is one input, and the cheaper option is not automatically the better buy: check what each side actually publishes in the feature and validation tables above before letting the dollar gap decide.

RingConn Gen 2 Air

$199

$199 hardware + $0 required subscription

RingConn Gen 2 costs $100 more than RingConn Gen 2 Air over 3 years. Cost is one input, and the cheaper option is not automatically the better buy: check what each side actually publishes in the feature and validation tables above before letting the dollar gap decide.

Ultrahuman Ring PRO

Free ring data, plugs optional

$479

$479 hardware + $0 required subscription

Ultrahuman Ring PRO costs $280 more than RingConn Gen 2 Air over 3 years. Cost is one input, and the cheaper option is not automatically the better buy: check what each side actually publishes in the feature and validation tables above before letting the dollar gap decide.

Ultrahuman Ring AIR

Ultrahuman Ring PRO costs $130 more than Ultrahuman Ring AIR over 3 years. Cost is one input, and the cheaper option is not automatically the better buy: check what each side actually publishes in the feature and validation tables above before letting the dollar gap decide.

CUDIS 002 Classic

Both options total $349 over 3 years.

CUDIS 002 Sporty

$399

$399 hardware + $0 required subscription

CUDIS 002 Sporty costs $50 more than CUDIS 002 Classic over 3 years. Cost is one input, and the cheaper option is not automatically the better buy: check what each side actually publishes in the feature and validation tables above before letting the dollar gap decide.

The right pick depends on what you value.

Four common buyer profiles with our pick for each. Use the finder above to weight it differently.

For the deepest feature set and the only validation record

Oura Ring 5

The widest published software list here, plus the only lineup in this comparison pointing at independent peer-reviewed accuracy studies and a medical advisory board. Every insight beyond the three daily scores needs the membership, which is why it is also the most expensive over time.

$399

· ~$603 / 3 yrs

For no subscription and the most complete package

RingConn Gen 3

Everything unlocked at purchase, 14-day rated battery, the wireless case in the box, plus sleep apnea pattern monitoring and nighttime vascular trends no other ring here lists. $349 flat, or step down to the $199 Gen 2 Air for the cheapest ring in this comparison, which drops apnea monitoring.

$349

· Gen 2 Air $199

For the longest battery and a whole-body ecosystem

Ultrahuman Ring PRO

Fifteen rated days, up to 45 with the case, 250 days of on-ring storage, and a first-party CGM, blood-panel and home sleep stack feeding one AI layer. It is a US pre-order, the full PowerPlug set is a real $133/yr on top, and no independent study has tested it.

$479

· pre-order in the US

For changeable styling with no recurring fee

CUDIS 002 Sporty

The only ring here with interchangeable bands, 12 of them, plus a Sports Mode and a battery two testers beat the claim on. Go in knowing what is missing: no published spec sheet or accuracy figure of any kind.

$399

· Classic $349

Accuracy honesty

All four publish claims. Only one has been independently checked.

No ring here is a medical device and none holds an FDA clearance of its own. The difference between these brands is not the sensor, it is who has verified the output. One caution: an absent study is not a failed study. Three of these brands have not been independently tested, so their accuracy is unknown rather than bad, which is a real risk but a different one.

Oura's posture

The only brand here that points to peer-reviewed validation studies it did not run, plus a medical advisory board. That is the strongest evidence base here, not proof of accuracy: being measured is not the same as scoring well, and several studies find Oura poor on specific metrics. Its own marketing is still marketing. "Research-grade" and a pulse signal "up to 100x stronger" than a wrist device are unverified company claims, and roughly 5M paid members and a 2026 IPO filing are scale, not evidence.

Independent peer-reviewed studies

RingConn's posture

Lists strong per-metric figures on the Gen 3 page (HR over 98%, SpO2 under 1.9% MAE, sleep time over 99%, steps over 95%) with no method published alongside them. Its strongest external evidence is a Ruijin Hospital feasibility study presented at IEEE AICAS 2024: 230 volunteers, r=0.93 against a sleep lab for apnea patterns.

Marketing stats + one feasibility study

Ultrahuman's posture

PubMed returns zero results for "Ultrahuman ring," and Dial 2025, the five-device head-to-head against a Polar H10 ECG, did not test it. Its published heart-rate work is six volunteers over six days compared against an Apple Watch and another consumer ring, which is device-to-device agreement, not validation. Its flagship Frontiers paper (n=442) was written by seven Ultrahuman employees including the CEO and states outright that no laboratory VO2 max comparison was performed.

In-house only, largest study n=6

CUDIS's posture

No study, no third-party testing, and not a single per-metric number on any CUDIS surface. The claims it does make are outcome claims rather than accuracy ones: "15 more hours of deep sleep per month" and "30% less chance of getting injury" come from internal data with no sample definition, no control group and no stated method. That is the youngest evidence base of the four, and it cuts both ways: nobody outside the company has tested these rings, so the accuracy is unknown rather than poor.

No published accuracy data

Every cell above is the company's own claim or the absence of one. Because Ultrahuman's and CUDIS's figures come from in-house or no testing at all, this page will not table them beside the lab-referenced MAPE figures used on our accuracy tools. That would imply a comparison the evidence cannot support. RingConn's 90.7% apnea figure is a Gen 2 product-page marketing number, cited as such, and its apnea feature is "not intended to diagnose." Oura's Blood Pressure Signals and breathing features are likewise not FDA-cleared.

Before you buy

Four things the product pages will not tell you.

Each of these changes what you are actually buying, and each one is documented on a primary source rather than a review.

Two Ultrahuman rings cannot legally ship to a US address

Oura brought ITC investigation 337-TA-1398 as complainant. The Commission found Ultrahuman infringed Oura's US Patent 11,868,178 and issued a limited exclusion order plus a cease-and-desist order in August 2025, with the bond set at zero percent. RingConn settled and took a royalty-bearing licence; Ultrahuman did not, and its Federal Circuit appeal is consolidated, briefed and still undecided, so the finding is not final. Only the redesigned Ring PRO enters the US, under CBP ruling HQ H354023 of March 6, 2026, because its unibody titanium tube falls outside the patent claims. The Ring AIR, the Diesel edition and the $1,799 Ring Rare are all blocked. This is a fact about what you can buy, not about the ring: a patent finding says nothing about whether a sensor is accurate.

Federal Register · CBP CROSS ruling HQ H354023 · Fed. Cir. 26-1083

The Ring PRO has now missed four US ship dates

The live page reads "Shipping September 15th onwards," after May 15 announced in March, June 20 announced as "shipping begins today," and August 10 given in a July Kickstarter update. Ultrahuman attributes the slip to per-unit finishing and the difficulty of scaling a titanium unibody with a cutaway safety feature, not to the legal case. Whether any US units actually shipped in June 2026 is not verified, and the continued pre-order language argues against it.

ultrahuman.com · Kickstarter updates · TechRadar

What is not in the box changes the price

The charging case, not the ring, is what turns a six-day battery into a multi-week one, and only two brands include one. Oura ships the Ring 5 with a pad only; the case that holds about five charges is a $99 add-on. Ultrahuman includes the PRO Charging Case with the Ring PRO, currently free, but the older Ring AIR ships with a pad and its Voyager charger is $45. RingConn puts a wireless case in the Gen 3 and Gen 2 boxes and a wired dock in the Gen 2 Air, with an optional $39.90 case. CUDIS includes a USB-C pod, though the $50 spare has been showing sold out. Compare ring plus case, not ring, or the cheapest column on this page is not the cheapest ring.

Each brand's own accessory and battery pages, verified September 2, 2026

"No subscription" means different things

RingConn and CUDIS charge nothing recurring and sell nothing recurring. Ultrahuman charges nothing to see your ring data but sells PowerPlugs: Cardio Adaptability at $2.90/mo, Cycle & Ovulation Pro at $3.99/mo, Tesla Sync at $6.90/mo, plus AFib detection, and Ultrahuman's own Ring Rare page values the full set at $133 a year. Oura is the only brand where the fee is not optional: without it you keep three daily scores and nothing else. Note too that RingConn markets its policy as permanent, but only Oura's membership terms are contractual per purchase.

Each brand's own pricing pages

Keep exploring

Related tools.

More free, evidence-based tools to get the most out of your wearable.

Depth vs value

Oura Ring vs RingConn

The two-brand deep dive: every spec across five models, the software matrix, and the no-subscription cost math.

Wearables · 5 models

Open

Relative thickness

Oura Ring 5 vs 4 vs 3

Every spec across three Oura generations, peer-reviewed accuracy, and the real 3-year cost.

Wearables · 3 generations

Open

Sleep staging vs PSG

Oura

Apple

Fitbit

Garmin

Most Accurate Sleep Tracker

Which wearable is most accurate for sleep vs a lab PSG? Compare 7 devices head to head.

Wearables · 14 sources

Open

FAQ

Common questions.

Which smart ring is the best in 2026?

There is no single winner, which is why this page ranks rings against your priorities. Oura leads on feature breadth and evidence: it is the only one of the four with independent peer-reviewed accuracy studies behind it. RingConn leads on value: no subscription, a 14-day rated battery on the Gen 3, the case in the box, and sleep apnea monitoring no other ring here offers. Ultrahuman leads on battery, 15 rated days, and its CGM and blood-panel stack, but the Ring PRO is still a US pre-order. CUDIS is the cheapest entry and the thinnest on published evidence.

Which smart ring has no subscription?

RingConn, Ultrahuman and CUDIS all charge nothing recurring for your own ring data. Oura is the exception: $5.99/mo or $69.99/yr is required for almost every insight beyond the three daily scores, putting a Ring 5 at roughly $603 over three years against $349 for a RingConn Gen 3. The wrinkle is Ultrahuman: ring data is free, but AFib detection and ovulation confirmation are paid PowerPlugs, and Ultrahuman's own page values the full set at $133 a year.

Which smart ring is the most accurate?

Strictly, nobody knows, because only one of these brands has been independently tested. Oura is the only ring here with peer-reviewed accuracy work behind it, so it is the only one whose accuracy is established at all, which is a different claim from being the most accurate. RingConn lists strong figures (heart rate over 98%, sleep time over 99%) without publishing the method; its strongest external evidence is a 230-volunteer hospital feasibility study. Ultrahuman has no independent validation: PubMed returns zero results, and its largest in-house study is six people against other consumer wearables. CUDIS publishes no accuracy figure at all.

Can you buy an Ultrahuman ring in the US right now?

Only the Ring PRO, and only as a pre-order. In ITC investigation 337-TA-1398 the Commission found Ultrahuman infringed an Oura patent and issued a limited exclusion order in August 2025. RingConn settled and took a licence; Ultrahuman did not, and its Federal Circuit appeal is undecided. The Ring PRO enters the US under CBP ruling HQ H354023 of March 6, 2026, because its unibody titanium tube falls outside the order. That covers only that design, so the Ring AIR, Diesel and Rare stay blocked. The Ring PRO page reads "Shipping September 15th onwards," the fourth promised date.

Does the CUDIS ring measure temperature?

Yes. Both 002 models carry a skin temperature sensor and the cycle features are derived from it. CUDIS confirmed this by email in September 2026; it is not stated on any CUDIS page, and no spec or accuracy figure has been published for it.

Is the CUDIS crypto reward worth anything?

In cash terms, currently very little. The $CUDIS token launched on Solana in June 2025 and now trades near $0.001 at a market cap around $260,000, down roughly 99.6% from its high, and redemption excludes the US and Europe. Worth knowing too: CUDIS markets a "health data marketplace" while its binding privacy policy says "We do not sell Personal Data," and its iOS and Google Play privacy labels contradict each other. None of that bears on how well the ring measures you.

Which ring is best for cycle and ovulation tracking?

Oura and Ultrahuman, with RingConn close behind. Oura offers cycle insights, period prediction, pregnancy insights and pairing with Natural Cycles, the FDA-cleared birth-control app, which no other brand here lists. Ultrahuman has a free Cycle and Ovulation PowerPlug plus a paid Pro tier powered by OvuSense, though OvuSense's headline 99% figure belongs to its vaginal sensor, not skin temperature. RingConn does full-cycle prediction with temperature-dip ovulation detection at no subscription. CUDIS has a temperature sensor and says its cycle tracking uses it, but publishes no ovulation, period-prediction or pregnancy feature, so it is the thinnest option here.

Can Kygo use my smart ring data?

Yes, for most. Kygo connects directly to Oura, plus Apple Health, Fitbit, Garmin, WHOOP and Samsung Galaxy Watch. RingConn and Ultrahuman both sync to Apple Health and Google Health Connect, so Kygo reads their sleep, HRV and heart-rate data that way. CUDIS describes HealthKit and Health Connect support in its privacy policy but does not advertise it, and one App Store reviewer reports it not working, so treat that path as unverified.

Sources

Every claim, traceable.

Every price, spec and policy here was read on the company's own pages in September 2026, with the regulatory facts pulled from the primary record: the Federal Register, the CBP rulings database and the openFDA API. Independent reviews are used only where a manufacturer publishes nothing, and are labelled as such.

Oura official

Oura Store

ouraring.com

Oura official

Oura Ring 5 product + specs

ouraring.com

Oura official

Oura Ring 4 product + specs

ouraring.com

Oura official

Oura Membership

ouraring.com

Oura official

Membership support article

support.ouraring.com

Oura official

Sleep & Rest

ouraring.com

Oura official

Heart Health

ouraring.com

Oura official

Women's Health

ouraring.com

Oura official

Metabolic Health

ouraring.com

RingConn official

Gen 3 product + specs + FAQ

ringconn.com

RingConn official

Gen 3 landing (accuracy + vascular)

ringconn.com

RingConn official

Gen 2 product

ringconn.com

RingConn official

Gen 2 Air product

ringconn.com

RingConn official

Official compare table

ringconn.com

RingConn official

App features

ringconn.com

RingConn official

Ruijin Hospital OSAHS study (IEEE AICAS 2024)

ringconn.com

Ultrahuman official

Ring PRO buy page + Compare PRO vs AIR

ultrahuman.com

Ultrahuman official

Ring AIR global buy page + Technical Specifications

ultrahuman.com

Ultrahuman official

Diesel Ultrahuman Ring buy page

ultrahuman.com

Ultrahuman official

Ring Rare buy page (US sale blocked)

ultrahuman.com

Ultrahuman official

PowerPlugs catalogue and pricing

ultrahuman.com

Ultrahuman official

Smart Rings Terms of Sale (warranty, returns, UltrahumanX)

ultrahuman.com

Ultrahuman validation

Ultrahuman Science hub

ultrahuman.com

Ultrahuman validation

Sleep heart-rate pilot study (n=6, in-house)

ultrahuman.com

Ultrahuman validation

Frontiers in Digital Health, fitness age, n=442 (all authors Ultrahuman employees)

frontiersin.org

Ultrahuman validation

PubMed search "Ultrahuman ring" (0 results)

pubmed.ncbi.nlm.nih.gov

Ultrahuman validation

Dial 2025, Physiological Reports (Ultrahuman and CUDIS not tested)

pmc.ncbi.nlm.nih.gov

Ultrahuman validation

FibriCheck 510(k) K173872, the clearance behind Ultrahuman AFib

accessdata.fda.gov

Ultrahuman US legal record

Federal Register: ITC final determination, 337-TA-1398

federalregister.gov

Ultrahuman US legal record

CBP Headquarters Ruling HQ H354023 (Mar 6, 2026)

rulings.cbp.gov

Ultrahuman US legal record

Fed. Cir. docket 26-1083, Ultrahuman v. ITC

dockets.justia.com

Ultrahuman US legal record

TechRadar: Ring PRO backers still waiting after production issues

techradar.com

CUDIS official

CUDIS support correspondence, September 2026 (temperature sensor and temperature-based cycle tracking confirmed)

Email, not published on any CUDIS page

CUDIS official

002 Classic product page

cudis.xyz

CUDIS official

002 Sporty product page

cudis.xyz

CUDIS official

How CUDIS Works

cudis.xyz

CUDIS official

Warranty policy

cudis.xyz

CUDIS official

Aftersales / returns policy

cudis.xyz

CUDIS official

Privacy policy (health data types, temperature not enumerated, "we do not sell Personal Data")

cudis.xyz

CUDIS official

Sporty Kickstarter campaign

kickstarter.com

CUDIS official

$CUDIS price and market cap (CoinGecko)

coingecko.com

CUDIS independent hands-on

Wareable review, using an Oura Ring 5 as control

wareable.com

CUDIS independent hands-on

Techloy hands-on (connectivity and step-count problems)

techloy.com

CUDIS independent hands-on

New Edge Times review

newedgetimes.com

CUDIS independent hands-on

openFDA 510(k) and registration queries for CUDIS (0 records, controls returned results)

open.fda.gov

Show all 45 sources

Kygo Health

Stop Guessing. Start Knowing.

Home How It Works Blog Contact Privacy Terms

This content is for informational purposes only and is not medical advice. Always consult a qualified healthcare provider before making decisions based on wearable data. None of these rings is a medical device and none of these brands holds an FDA clearance for the features described. RingConn's sleep apnea and vascular features do not diagnose any condition or measure blood pressure; Oura's Blood Pressure Signals and breathing features are not FDA-cleared; Ultrahuman's AFib feature runs on FibriCheck's clearance (K173872), not Ultrahuman's own.

Prices, specs, warranty terms and availability read on the manufacturers' own pages and verified September 2, 2026. Regulatory facts from the Federal Register (ITC 337-TA-1398), CBP ruling HQ H354023 and the openFDA API. Sale pricing, promotions and stock change without notice. Last updated September 2026.

As an Amazon Associate, Kygo Health earns from qualifying purchases. Product links on this page are affiliate links; we may earn a commission at no extra cost to you.

© 2026 Kygo Health LLC. All rights reserved.

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