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1Fix the driver behind crashes, sound loss and screen glitches2Clear out junk files and repair common Windows errors3Scan for outdated or missing drivers - takes under a minuteCircular Ring 2’s headline difference is a single-lead ECG sensor paired with software that screens for possible atrial fibrillation (AFib). It launched after its CES announcement in January 2025, but that feature does not make it a diagnostic device, and independent reviewers have reported problems with the app and ECG/AFib reliability. At $349 on Circular’s US product page, it starts at the same listed price as Oura Ring 4; Circular says core features have no recurring subscription, while Oura charges a US membership fee for many insights.
What Circular Ring 2 offers
Circular Ring 2 is a titanium smart ring designed to track sleep, activity, recovery and other health signals. Its listed sensors include ECG, photoplethysmography (PPG), skin temperature and a three-axis accelerometer. The accompanying app offers health insights and Kira AI coaching, and Circular says the ring works with iOS and Android.
Circular advertises more than 140 biometrics across 13 or more health features. A high metric count does not establish that each measurement is directly sensed, available in every region, or clinically accurate. The company’s product page also markets core features without a recurring subscription; that should not be read as a promise that every future or premium feature will always be free. Circular Ring 2 specifications and purchase information
Size, materials and battery claims
- Build: Titanium body with a hypoallergenic interior, according to Circular.
- Dimensions and weight: 2.55 mm thick, 7.8 mm wide and approximately 3 g.
- Sizes: US 6 through 14, with no half sizes. Circular offers a sizing kit; check its current terms before ordering.
- Battery: Circular claims up to 8 days in Power Mode or up to 5 days in Performance Mode. Actual life can vary with ring size, measurement frequency, ECG use, firmware and app behavior.
- Charging: The company lists about 30 minutes using its wireless charger.
Circular describes the ring as suitable for showers, pools and rain, but the cited product details do not establish a specific water-resistance rating. Check the current manual for the rating and use limits rather than assuming it is suitable for every water activity.
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- 【Check the Size Before Purchase】 Before buying the BIEMHA Smart Ring, we strongly suggest that you refer to the size chart and carefully measure the circumference of your finger. This will ensure you get the most comfortable wearing experience and easily avoid any unnecessary returns or exchanges.
- 【Real‑time Accurate Sleep & Fitness Monitoring】 BIEMHA smart ring tracks your sleep quality and daily activities in real time. With advanced sensors, it provides precise data about your sleep cycle, helping you optimize rest and recovery. Whether you are tracking steps, calories or exercise performance, this smart ring can provide you with the most accurate insights to support your fitness goals and enhance your overall health.It is a good choice for family and friends.
- 【Health Monitoring】The BIEMHA ring features advanced 4.0 sensors that automatically measure your heart rate every 30 min when worn. It provides continuous health tracking and comprehensive wellness management all day.
- 【2‑3 Day Battery Life】 With a 2‑3 day battery life, the BIEMHA smart ring ensures continuous health monitoring without frequent charging. When used with the smart charging case, the usage time can even exceed 5 days. Whether you are tracking sleep patterns or fitness activities, you can count on long‑lasting performance without constant interruptions.
- 【80‑meter Waterproof, Suitable for Various Scenarios】 The BIEMHA Smart Ring has excellent waterproof performance, with a waterproof depth of up to 80 meters. Whether it's for daily wear, an intense workout session or a pleasant swimming time, it can handle it with ease. What's more, even if you have sensitive skin, you can still enjoy an extremely comfortable wearing experience when wearing this ring.
What the ECG and AFib screening mean
An electrocardiogram (ECG) records electrical signals associated with the heart’s rhythm. Circular Ring 2 uses a single-lead design: it is not equivalent to a full 12-lead ECG performed in a clinical setting, nor does the presence of ECG hardware mean the ring continuously monitors the heart like a medical monitor. Follow the app’s instructions for a recording; Circular says recordings can be shared with a doctor.
AFib, or atrial fibrillation, is an irregular heart rhythm associated with increased stroke risk. The ring’s software analyzes ECG-derived signals for patterns consistent with AFib. A screening result can flag a possibility; it cannot independently confirm or rule out the condition. False positives and false negatives are possible, and an episode may not occur during a recording.
Rank #2
- 【Size Before You Buy】Before purchasing the Milavan Smart Ring, we recommend referring to the size chart and carefully measuring your finger circumference. This helps ensure a comfortable fit and avoid unnecessary returns or exchanges
- 【Wellness Tracking】The slim ring features advanced 4.0 sensors that automatically track your heart rate every 30 minutes while worn. Daily data is available in the app for reference only and is not intended for medical use
- 【Intelligent Sleep Tracker】The fitness ring automatically tracks your sleep quality, including deep and light sleep, REM (eye movement), and awake periods. You can view all sleep data anytime in the app for daily reference
- 【8 Sports Modes Tracking】Supports 8 sports modes, including Running, Cycling, Jump Rope, Walking, Hiking, Yoga, Dancing, and Golf. View workout duration, steps, heart rate, speed, calories burned, distance, and other activity data in the app
- 【Stylish Fitness Companion】Featuring a slim 2mm profile and a specially polished inner surface, this smart ring is designed for comfortable all-day wear and most sports activities. View detailed workout data in the app after selecting a sport mode
Launch coverage described the AFib algorithm as FDA-cleared, but that wording is not the same as saying the entire ring is FDA-approved. Regulatory status applies to a specific device or software and its permitted use; it does not make a consumer reading a diagnosis. The FDA explains medical-device terminology and oversight at FDA: Medical Devices. Circular’s current country, app-version and labeling details should be checked before relying on the feature. Wareable’s CES coverage discusses the clearance claim.
If you receive an alert—or no alert
- If the app provides an ECG recording or export, save it and contact a healthcare professional for interpretation. Tell them about symptoms, medicines and any known heart conditions.
- Do not treat a single alert as a diagnosis, and do not treat the absence of an alert as proof that AFib or another heart problem is absent.
- Chest pain, fainting, severe shortness of breath or sudden weakness warrant urgent medical attention. Do not wait for a ring reading or repeat measurements instead of seeking care.
Price and subscription: Circular versus Oura
Circular’s US product page lists Ring 2 at $349. Oura lists the base Ring 4 from $349 in the US, but many Oura insights require membership. Oura’s US membership is $5.99 per month or $69.99 per year before applicable taxes; new members get the first month free, according to its membership terms. Store totals can vary by location, tax, finish or promotion, so confirm checkout pricing.
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Rank #3
- 【Ultra-Thin & Lightweight Design】Our smart ring is thinner and lighter than others, and is designed for all-day comfort. Its ergonomic, globular gluing process ensures a perfect fit for your finger, providing a comfortable experience even during extended wear.
- 【Comprehensive Health Tracking】Keep track of your health with health monitoring features, including heart rate detection, blood oxygen level, stress analysis, sleep tracking and step counting. Instantly understand your body metrics and help you manage your health indicators scientifically.
- 【Long-Lasting Battery Life】Enjoy up to 5 days of regular use on a single charge, eliminating the need for frequent recharging. Whether you're working out or on the go, the smart ring's efficient battery ensure uninterrupted usage.
- 【10ATM Waterproof & Remote Camera Control】Built with 10ATM waterproof technology, this smart ring is perfect for swimming, showering, and other water activities. Plus, its innovative remote camera control feature lets you capture photos effortlessly by simply waving your hand—ideal for capturing life's special moments.
- 【No Subscription Fees】Accessing your health data through a mobile app, with no subscription fees, is an affordable and easy-to-use option for your health journey!
| Option | Listed US ring price | Recurring fee and qualification |
|---|---|---|
| Circular Ring 2 | $349 on Circular’s product page | Circular says core features have no recurring subscription; premium or future features may have separate terms. |
| Oura Ring 4 | From $349 on Oura’s store | $5.99/month or $69.99/year before tax; first month free for new members. Oura store |
| Samsung Galaxy Ring | Not stated here | Check Samsung’s current price and terms for your market. Samsung US Galaxy Ring |
The subscription difference matters most if you plan to keep the ring for several years and want access to detailed insights. Circular’s no-recurring-fee claim is an advantage for its advertised core functions, not proof that all roadmap features or premium analytics are included indefinitely.
How it compares with Oura Ring 4 and Galaxy Ring
| Question | Circular Ring 2 | Oura Ring 4 | Samsung Galaxy Ring |
|---|---|---|---|
| ECG and AFib | Advertises single-lead ECG and ECG-based AFib screening; availability and regulatory labeling can depend on market and software. | Oura’s cited Ring 4 specifications do not identify ECG as a feature. | No ECG feature is identified in the ring itself in the cited comparison information. |
| Primary appeal | Distinctive heart-rhythm screening, broad wellness tracking and subscription-free core features. | Established sleep, recovery, stress and wellness analytics, with a membership for many detailed insights. | Convenience for people already using Samsung Galaxy phones, watches and Samsung Health. |
| Compatibility | iOS and Android, according to Circular. | iOS and Android, according to Oura’s product information. | Check current compatibility and feature availability; the strongest fit is generally within Samsung’s ecosystem. |
| Battery claim | Up to 8 days in Power Mode or 5 days in Performance Mode, per Circular. | Oura lists 5–8 days depending on size and use. | Check Samsung’s current model information for the relevant market. |
| Software maturity | Reviewers reported bugs, synchronization issues and inconsistent ECG/AFib operation. | Independent comparisons describe Oura’s app and analytics as more mature. | Most useful to buyers who value Samsung Health and connected Galaxy devices. |
Oura Ring 4 uses a titanium design with recessed interior sensors, and Oura’s listed battery range is 5–8 days depending on size and use. Its official specifications emphasize wellness and cardiovascular metrics rather than ECG. Oura Ring 4 specifications
Rank #4
- THE WORLD’S SMALLEST SMART RING - 40% smaller than the previous generation, Oura Ring 5 is thinner, lighter and smaller than ever. The updated all-titanium design is more scratch-resistant and comfortable than ever
- SIZING IS ESSENTIAL - Oura Ring 5 uses unique sizing different from standard jewelry rings and other Oura Ring generations; use the Oura Ring 5 Sizing Kit to find your perfect fit before purchasing
- EVERYDAY HEALTH SENSING - Oura tracks over 50 health metrics, including sleep, activity, stress, heart health, metabolic health and women’s health metrics. Oura seamlessly integrates with over 40 apps including Natural Cycles, Strava, & more
- OURA MEMBERSHIP - First month of membership is included with purchase, for new members only. Subscription is 5.99/mo afterwards. Membership is tied to your account via the Oura App, not your physical ring
- REBUILT FOR GREATER ACCURACY - Oura Ring 5 has been re-engineered and reconfigured, providing more precise personal health data. Larger, smarter sensors bring research-grade accuracy—all in Oura’s smallest form factor yet
There is no universal winner. Circular’s ECG is the clearest hardware distinction; Oura is the safer choice if polished software and established sleep and recovery analytics matter more. Galaxy Ring makes the most sense when Samsung Health and the wider Galaxy setup are central to the purchase, rather than as a substitute for ECG.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What independent reviews found
The practical caveat is that a distinctive sensor only helps if the recording, app and data flow work reliably. TechRadar reported inconsistent ECG and AFib operation, software bugs and synchronization problems, and noted that promised blood-pressure and glucose-trend functions were not available during its review. It also found Sports Sessions required manual activation rather than matching the automatic workout experience offered by more established rivals. TechRadar’s Circular Ring 2 review
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- 【Check the Size Before Purchase】 Before buying the Free Shark Smart Ring, we strongly suggest that you refer to the size chart and carefully measure the circumference of your finger. This will ensure you get the most comfortable wearing experience and easily avoid any unnecessary returns or exchanges.
- 【Intelligent Sleep Tracker, Caring for Your Health】 This Free Shark fitness ring is like a considerate little assistant for your sleep health. It will accurately monitor the quality of your sleep, and record in detail the durations of deep sleep and light sleep, as well as the specific situations of your wakeful states. You just need to open the app at any time, and you can clearly view all kinds of sleep indicators. Then, according to the professional reports, you can easily adjust your lifestyle to embrace better-quality sleep.
- 【Diverse Health Monitoring, All-round Protection】 The Free Shark Smart Ring has a variety of powerful health monitoring modes. Whether it's running, walking, hiking, cycling, yoga, dancing, skipping rope or other sports, it can automatically and accurately track key data such as the exercise route, exercise time, steps taken, heart rate, speed, calories burned and exercise distance in the app. Moreover, it can continuously track important health data such as heart rate and blood oxygen throughout the 24 hours of the day, protecting your physical health in an all-round way.
- 【80-meter Waterproof, Suitable for Various Scenarios】 The Free Shark Smart Ring has excellent waterproof performance, with a waterproof depth of up to 80 meters. Whether it's for daily wear, an intense workout session or a pleasant swimming time, it can handle it with ease. What's more, even if you have sensitive skin, you can still enjoy an extremely comfortable wearing experience when wearing this ring.
- 【Long Battery Life and Ultra-thin Design, Enjoy the Convenience】 The Free Shark Smart Ring has a very strong battery life. After a full charge, the battery can last up to 5 days, easily keeping up with your busy lifestyle. When used with the smart charging case, the usage time can even exceed 30 days. It is widely compatible with both Android and iOS systems, which is very convenient and practical. In addition, the updated design is lighter, thinner and more comfortable, with a greatly improved wearing fit. It's so light that you can hardly feel it on your finger.
Tom’s Guide also described a wide feature set alongside software and data-transfer limitations. These are reviewer findings, not proof that every unit or current software version behaves identically; they are nevertheless important evidence for buyers who need dependable daily syncing or intend to use the heart-rhythm feature. Tom’s Guide’s three-week review
Promised features versus confirmed availability
Blood-pressure and glucose-trend monitoring have appeared as future or premium additions in Circular’s product messaging. The company’s product pages have shown shifting projected dates, so these should be treated as roadmap items unless the current app and documentation confirm the feature is released for your country and plan. Circular Ring 2 feature and roadmap page
- A feature announced for the future is not the same as a feature available now.
- Check whether a function is in beta, country-limited or tied to a paid tier or credit.
- Do not buy the ring on the assumption that planned blood-pressure or glucose functions are already present.
Who should consider Circular Ring 2?
It may suit you if
- You specifically want ECG-based AFib screening in a ring form factor.
- You want to avoid a mandatory recurring fee for core features.
- You use iOS or Android and are comfortable with a newer product whose software has received mixed reviews.
- You are willing to treat its health readings as prompts for follow-up, not as medical answers.
Look elsewhere if
- You need clinically dependable heart monitoring or have been advised to use a medical device. A ring is not a replacement for a physician-ordered ECG, Holter monitor or patch monitor.
- Reliable synchronization, polished analytics or automatic workout detection is your top priority.
- You need half sizes or a size outside US 6–14.
- You want to buy based on blood-pressure or glucose-trend tracking before those features are confirmed as available to you.
For buyers whose real need is a screen, richer workout controls or a more established ECG workflow, a smartwatch may be a better category to compare. Apple Watch and Samsung Galaxy Watch product pages provide starting points: Apple Watch and Samsung Galaxy Watch. A medically indicated monitor should be selected with a clinician, not substituted with a consumer ring.
Bottom line
Circular Ring 2 is worth considering if ECG and AFib screening plus avoiding a core-feature subscription are your main priorities. Its $349 US listing puts it in the same starting-price territory as Oura Ring 4, but independent reports of software and signal reliability issues make it a less reassuring all-around choice today. Choose Oura for a more established wellness experience, or Galaxy Ring for Samsung ecosystem convenience; choose a medical device or smartwatch when your need is dependable cardiac monitoring rather than discreet wellness tracking.
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
