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See prices, running costs, specifications and trade-offs side by side. Choose two to four products of the same type.

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Smart ring

RingConn Gen 3

Matte Black finish, sizes 6 to 15 (or 'Don't know my size' with the free Gen 3 sizing kit), charging case included

$349US price, checked Oct 13, 2026

Subscription-free sleep and recovery ring with up to 14 days of battery

Check price at RingConn Full review →

Smart ring

Oura Ring 4

Silver finish, plus Oura Membership billed separately

$349US price, checked Oct 13, 2026

Oura's previous-generation smart ring, with the membership billed separately

Check price at Oura Full review →

Our no-membership ring pick

Ultrahuman Ring PRO

Aster Black finish, whole sizes 5 to 14, with PRO Charging Case

$479US price, checked Oct 13, 2026

Subscription-free titanium ring with its charging case included

Check price at Ultrahuman Full review →

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Criterion	RingConn Gen 3	Oura Ring 4	Ultrahuman Ring PRO
US price	$349Checked Oct 13, 2026 · Price details in the review	$349Checked Oct 13, 2026 · Price details in the review	$479Checked Oct 13, 2026 · Price details in the review
Three-year ownership estimate	$349 Incomplete known subtotal. Not included: energy use.	$558.97 Incomplete known subtotal. Not included: energy use.	$479 Incomplete known subtotal. Not included: energy use.
Choose if	You wear a size 6 to 15, want overnight sleep, HRV and temperature trends from a ring, and would rather pay $349 once than pay a yearly membership.	You want Oura's sleep, heart-rate and temperature-trend tracking in the previous-generation ring and don't need Ring 5's smaller size.	Anyone in a whole ring size from 5 to 14 who wants long battery life and would rather pay $479 once than pay a yearly membership.
Main trade-off	The page gives no accuracy data for the vascular and sleep apnea insights, returns within 14 days need a valid reason such as a defect or wrong color, and the 1-year US warranty excludes battery replacement.	You pay a yearly membership for full features, and Oura says Ring 5 is 40% smaller with greater accuracy and battery power.	Ultrahuman publishes no Ring PRO accuracy figures on the pages checked, some features are paid PowerPlugs, and theft and loss cover needs the $54 two-year UltrahumanX plan.
Key specifications	Battery life: Up to 14 days: 10 to 12 days with vibration on, 11 to 14 days with it off. Charging takes about 90 minutes for the ring and about 120 minutes for the case Sensors: Optical heart-rate sensor, temperature sensor, 3-axis accelerometer and vibration feedback motor Subscription: None. The page says 'No Subscription Required' Metrics tracked: Around the clock: heart rate, HRV, SpO2, respiratory rate, skin temperature, stress, steps and calories. During sleep: sleep duration, sleep stages, sleep apnea risk indicators and overnight vascular load trends Water resistance and operating range: IP68 / 10 ATM, to 100 m (328 ft). Operating temperature 32°F to 104°F (0°C to 40°C) Sizes: 6 to 15, plus a 'Don't know my size' option. Gen 3 uses a different sizing system from earlier RingConn rings. RingConn recommends its free sizing kit, which it sends before the ring ships Thickness and weight: 2.3 mm thick, 2.5 to 3.5 g Data and compatibility: The ring stores 10 days of data offline. Works with iOS 17.0 or later and Android 10.0 or later over Bluetooth 5.0. Syncs with Apple Health and Google Health Connect US import status: Not barred. An August 2025 US International Trade Commission (ITC) order barred imports of RingConn rings that infringe an Oura patent. RingConn then settled with Oura and licensed the patent, so in December 2025 the ITC removed RingConn from the order	Battery life: 5 to 8 days. A charge typically takes 20 to 80 minutes, depending on battery level. Oura says battery life and longevity depend on ring size, app settings and feature configuration Sensors: Red and infrared LEDs for blood oxygen. Green and infrared LEDs for heart rate, heart rate variability and respiration rate. A digital temperature sensor and an accelerometer Membership: $5.99 a month or $69.99 a year in the US, before tax. New members get the first month free. The ring has limited functionality without it Water resistance: Up to 100 m (328 ft) Compatibility: iOS and Android Connectivity: Bluetooth Low Energy, with airplane mode support. Firmware updates come through the Oura App. Oura lists the ring as FCC-certified Weight: 3.3 to 5.2 g depending on size	Battery life: Up to 15 days (about 12 days in Turbo Mode, 15+ days in Chill Mode). Up to 45 days between wall charges with the PRO Charging Case. About 2.5 hours for a full charge. Sensors: Temperature sensor, redesigned PPG sensor and 6-axis IMU. Dual-core processor with on-chip machine learning. Subscription: No recurring subscription fees for accessing your data. Optional PowerPlugs cost extra. Cardio Adaptability, for example, is $24 for 1 year or $38 for 2 years. Cycle & Ovulation Pro is $39 for 1 year or $69 for 2 years. Data storage: Up to 250 days of data on internal and external flash, per Ultrahuman's comparison page. Up to 1 year of ring data backed up to the PRO Charging Case. Water resistance: 100 m (328 ft) Sizes: 5 to 14, no half sizes. Ultrahuman says its sizes may differ slightly from standard US ring sizes. Weight and thickness: 3.3 to 4.8 g depending on size. 2.65 mm thick (varies by size).
Exact variant	Matte Black finish, sizes 6 to 15 (or 'Don't know my size' with the free Gen 3 sizing kit), charging case included	Silver finish, plus Oura Membership billed separately	Aster Black finish, whole sizes 5 to 14, with PRO Charging Case
Dimensions	2.3 mm thick, weighing 2.5 to 3.5 g. RingConn's product page doesn't state the band width or the inner diameter of each size.	7.90 mm wide and 2.88 mm thick. It weighs 3.3 to 5.2 g, depending on ring size.	It's 2.65 mm thick, though thickness varies by size. It weighs 3.3 to 4.8 g depending on size. Ultrahuman doesn't state band width or per-size inner diameter on the pages checked.
Installation	No installation. If you don't know your Gen 3 size, choose the free sizing kit option ('Don't know my size') when you order. RingConn says it sends the kit before the ring ships, and that the kit arrives in 3 to 8 days, depending on location. You then submit your size under 'My Orders'. The ring pairs with your RingConn App account over Bluetooth 5.0, on iOS 17.0 or later or Android 10.0 or later. RingConn lists the box contents as the Gen 3 ring, a charging case, a USB-C charging cable and a quick start guide.	No installation. It pairs with the Oura app on iOS or Android. It charges on the included size-specific charger with a USB-C cable. Oura offers a free sizing kit with plastic sizers before you order.	No installation. It pairs over Bluetooth (BLE 5.3) with the Ultrahuman app, which is on the App Store and Google Play. In the box are the ring, the Ring PRO Charger and a 1 m USB-C to USB-C cable. Ring PRO charges only on the PRO Charger or PRO Charging Case, not on a Ring AIR charger. Before you order, Ultrahuman offers a free sizing kit with plastic sizers in sizes 5 to 14.
Materials	Titanium alloy, with medical-grade epoxy and a PVD coating. RingConn's FAQ describes the matte finish as non-reflective and understated.	The inner and outer surfaces are titanium, and the interior has no seams. Oura says minor scratches from regular wear are normal.	The ring is titanium with a PVD coating, plus epoxy and polycarbonate. Ultrahuman says the inner surface is hypoallergenic plastic and titanium. The charging case is aluminum, stainless steel and plastic.
Warranty	The warranty runs 1 year from delivery in the US and everywhere else outside the EEA. EEA countries get 2 years. RingConn's Return & Refund Policy says it will repair, replace or refund if a defect in its workmanship causes damage, with proof of purchase. It excludes improper or negligent use, maintenance contrary to instructions, normal wear and tear and accidental damage. The policy calls rechargeable batteries consumables with a limited lifespan, and the standard warranty doesn't include battery replacement. It doesn't say whether cosmetic damage or loss is covered.	A 1-year protection plan is included with purchase. The product page offers upgrades to 2 years for $45 or 3 years for $60.	A 12-month limited warranty runs from delivery and covers defects in materials and workmanship. It's valid only in the country of purchase. The Terms of Sale, which don't name Ring PRO, exclude consumable parts such as batteries or protective coatings unless a defect caused the failure. They also exclude accidents, misuse and normal wear and tear. Cosmetic damage such as scratches and dents isn't covered unless a defect caused it. Upgrading through trade-in resets the warranty. Optional UltrahumanX coverage costs $36 for 1 year, with accidental damage protection and priority care. The $54 plan for 2 years adds theft and loss protection and what Ultrahuman calls weight loss insurance.
Returns	The product page advertises '14-Day Returns & Exchanges', with conditions applying and sizing kits excluded. The fine print is in RingConn's Return & Refund Policy. You have to request a return within 14 calendar days of delivery. Returns and exchanges both need a valid reason. The policy lists a defect or damage on delivery, a color different from the one you ordered, or a product that differs significantly from its description. The returned ring must also be in its original condition and, in the policy's words, one that 'has not been opened and used'. You pay return shipping, and shipping, handling and tax aren't refunded. The exceptions are a return for a defect, damage or non-conformity you documented with photos in advance, or one caused by RingConn's error. No restocking fee is stated, but RingConn may deduct for damage, wear or missing parts. Sizing kits are non-refundable and non-returnable. Canceling after a kit has shipped costs $10. For a different size or color, the policy recommends a return request and a new order.	If you bought the ring directly from Oura's online store, you can return it within 30 days of receiving the order. It has to be fully functional and undamaged, and come back with the charger and USB-C cable. Ring sets can't be partly returned. Exchanges are only for a different size of the same ring, and each item can be returned or exchanged once. Refunds go to the original payment method, but original shipping and handling aren't refunded. Rings bought from other retailers follow that retailer's policy. Oura's return FAQ says to cancel the membership when you return a ring. The Ring 4 Silver product page says canceling doesn't entitle you to a full or pro-rated refund of fees you've paid. Warranty replacements can't be returned for a refund.	If you're not completely satisfied, you can return it within 30 days of delivery. Send it back in the original packaging with all original accessories, including the charger. The Ring PRO FAQ and the Smart Rings Terms of Sale both say return shipping is free. No restocking fee is stated. The Terms of Sale list these return terms under the Ring AIR heading, and the FAQ applies them to Ring PRO.
Unresolved questions	Whether RingConn's policy counts a poor fit or a sizing mistake as a valid reason for a return or exchange Whether cosmetic damage or loss is covered What an out-of-warranty battery replacement or repair costs The band width and the inner diameter of each size How the vascular health trend and overnight vascular load are calculated, and whether they've been validated against clinical measures Independent, peer-reviewed accuracy data for Gen 3 against polysomnography, ECG or a home sleep apnea test How many ring charges the case holds The battery's lifespan and the charger's power draw How long RingConn will keep features free of charge and keep supporting Gen 3	Who pays return shipping, which Oura's return FAQ doesn't say How long Oura will keep selling and supporting Ring 4 now that Ring 5 is on sale How accurately Ring 4 itself stages sleep against polysomnography Battery lifespan, out-of-warranty replacement cost and charging power draw The FDA regulatory status of Ring 4 features, which the pages checked didn't confirm	Band width and per-size inner diameter Whether a worn-out battery is repaired or replaced at a cost, since the Terms of Sale exclude battery wear from the limited warranty Independent, peer-reviewed accuracy data for Ring PRO against polysomnography or ECG Battery lifespan, out-of-warranty replacement cost and charger power draw Renewal prices for PowerPlugs after the first term Minimum supported iOS and Android versions How long Ultrahuman will sell and support Ring PRO in the US

These comparisons use published specifications, not head-to-head tests. Prices and terms are dated. Unknown costs are not zero. Check the exact variant before you buy.