The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Circular announced the Circular Ring 2 at CES 2025 with a built-in single-lead ECG sensor and software for heart-rhythm and AFib analysis. That makes it one of the more unusual smart rings: it is designed to record electrical heart activity, not just estimate pulse and recovery through optical sensors. Circular later listed the ring at $349 and said its core health features do not require a subscription.
There is an important qualification. The ECG hardware is real, but the Ring 2 is not a hospital ECG or a replacement for medical assessment. Circular says the ring as a whole is not classified as a medical device, and independent reviewers reported software, synchronization and ECG-usability problems during early testing.
As an Amazon Associate I earn from qualifying purchases.
What Circular announced at CES 2025
The announcement took place in Las Vegas in January 2025. Circular presented the Ring 2 as a health-focused smart ring with integrated ECG hardware, heart-rhythm monitoring and AFib-related analysis. The company also announced digital ring sizing alongside the health features.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →The ECG is not merely an app feature. Circular’s product specifications list ECG among the onboard sensors, while an FCC filing identifies a single-lead ECG sensor. The ring also combines ECG with PPG, temperature sensing and three accelerometers.
#1 Best Overall
- Adaptive-Fit Design: Revolutionary technology automatically adjusts to finger size changes throughout the day. Perfect skin contact ensures accurate readings while maintaining comfort. Fits multiple fingers without sizing kits.
- Advanced Sleep Monitoring: Tracks your sleep patterns and oxygen levels throughout the night, providing insights to help you understand your sleep better.
- Real - time SpO2 Tracking: Continuously monitors your blood oxygen levels in real - time, keeping you informed of your body's oxygen status. Monitors heart rate, HRV, SpO2, activity, stress, and temperature. OTA updates ensure latest features, while the app provides trend analysis and personalized insights.
- No Subscriptions, Extended Battery: One-time purchase unlocks all features permanently. 4 - 7 day battery life with 120+ additional hours from portable charging case. iOS/Android compatible with Apple Health sync. 5 ATM waterproof.
- Professional Fitness Tracking: Accuracy rivals chest straps with multiple sport modes, real-time monitoring, and customizable goals to optimize training effectiveness.
That distinction matters: the ring contains the hardware needed to capture an electrical signal, while the Circular app and its algorithms interpret and display the result.
What a single-lead ECG can—and cannot—tell you
A single-lead ECG records the heart’s electrical activity through one measurement pathway. It can provide a useful rhythm snapshot and may help flag patterns associated with an irregular rhythm. It is not equivalent to the 12-lead ECG used in a clinical setting, which measures the heart from multiple electrical viewpoints.
A Ring 2 reading can be affected by fit, skin contact, finger position, movement, moisture, electrical noise, firmware, Bluetooth and app performance. A possible AFib or irregular-rhythm result should therefore be treated as a screening signal to discuss with a healthcare professional—not as a definitive diagnosis. Conversely, a normal consumer reading does not rule out every heart problem.
Circular markets the feature as AFib detection and heart-rhythm analysis, but the available material does not establish a precise monitoring schedule or guarantee continuous diagnostic monitoring. Buyers should check how the current app handles recordings and results rather than assume the ring works like a continuously supervised clinical monitor.
Rank #2
- [AI-Powered Health Insights] RingConn Gen 2 Air Smart Ring integrates AI with multi-sensor data to continuously track key health metrics like sleep, heart rate, stress levels, blood oxygen, physical activity, and menstrual cycles. Its built-in AI assistant delivers your personalized report and guidance to enhance your wellness and daily habits
- [Size Before You Buy] RingConn Gen 2 Air uses unique sizing standards, different from standard ring sizes. Purchase RingConn Sizing Kit to find the most accurate and comfortable fit for your finger
- [No-Feel Wearing] Experience a comfortable, stylish design with a super-thin 2mm profile and only 2.5g weight. Won't interfere with your movement whether you're working out, running, diving, or engaging in any physical activity, and stays comfortable without distracting you when sleeping or working
- [No Subscription Fee for Standard Features] Unlock the lifetime use of essential standard features on the RingConn Smart Health Monitoring App with your RingConn Gen 2 Air Smart Ring. Experience continuous, real-time health tracking and personalized insights
- [Longer Battery Life] Enjoy up to 10 days of uninterrupted power with a single full charge that completes in just 90 minutes. Stay powered through your busy schedule without frequent recharging and efficiently maintaining continuous long-term data collection
Announcement, crowdfunding and availability timeline
- January 2025: Circular announced the Ring 2 and its ECG functionality at CES 2025. TechCrunch reported the announcement.
- March 5 to April 14, 2025: Circular ran its Kickstarter campaign.
- July 2025: Circular’s release notes documented Ring 2 support and the Heart Rhythm feature in the app.
- Late 2025 into 2026: Independent reviews described the product reaching customers progressively after its crowdfunding launch.
- Later retail listing: Circular’s store listed the Ring 2 at a $349 starting price. Check the store for the current price, regional availability and delivery terms.
These are different milestones. A CES announcement did not mean the ring was broadly available that day, and the presence of ECG hardware did not necessarily mean every related app function was mature at launch.
Specifications and claimed battery life
The following figures come from Circular’s product listing and should be treated as manufacturer specifications:
| Specification | Circular’s stated figure |
|---|---|
| Starting price | $349 |
| Sizes | US 6–14 |
| Body | Titanium |
| Weight | 3 grams |
| Thickness | 2.55 mm |
| Width | 7.8 mm |
| Battery | Up to eight days in Power Mode; five days in Performance Mode |
| Charging | Approximately 30 minutes, wirelessly |
| Sensors | ECG, PPG, temperature and three accelerometers |
| Phone compatibility | iOS and Android |
| Subscription | No subscription for core features, according to Circular |
Circular also advertises more than 140 biosignals and more than 13 health features, including sleep, activity, recovery, stress, energy, women’s health tracking and AI coaching through Kira. Battery life can vary with settings, measurement frequency, connectivity and software updates.
Recommended Free Tools
Subscription-free does not mean every feature is free
Circular says the core health and biometric feature set is included without a recurring subscription. That is a meaningful difference from subscription-based smart-ring models.
Rank #3
- [AI-Powered Health Insights] RingConn Gen 2 Air Smart Ring integrates AI with multi-sensor data to continuously track key health metrics like sleep, heart rate, stress levels, blood oxygen, physical activity, and menstrual cycles. Its built-in AI assistant delivers your personalized report and guidance to enhance your wellness and daily habits
- [Size Before You Buy] RingConn Gen 2 Air uses unique sizing standards, different from standard ring sizes. Purchase RingConn Sizing Kit to find the most accurate and comfortable fit for your finger
- [No-Feel Wearing] Experience a comfortable, stylish design with a super-thin 2mm profile and only 2.5g weight. Won't interfere with your movement whether you're working out, running, diving, or engaging in any physical activity, and stays comfortable without distracting you when sleeping or working
- [No Subscription Fee for Standard Features] Unlock the lifetime use of essential standard features on the RingConn Smart Health Monitoring App with your RingConn Gen 2 Air Smart Ring. Experience continuous, real-time health tracking and personalized insights
- [Longer Battery Life] Enjoy up to 10 days of uninterrupted power with a single full charge that completes in just 90 minutes. Stay powered through your busy schedule without frequent recharging and efficiently maintaining continuous long-term data collection
However, Circular also describes a freemium model involving paid features or Circular Coins. Blood-pressure and glucose-trend functions have been presented as planned, staged or premium capabilities rather than universally established core features. Their availability, timing and pricing may change, so buyers should not purchase the ring assuming every advertised future function is already active or permanently free.
What reviewers found in practice
The headline hardware does not tell the whole story. Reviews identified several software and usability caveats:
- Tom’s Guide reported app bugs, data-transfer problems and difficulty obtaining ECG readings during testing.
- TechRadar highlighted the ECG and AFib features but also raised concerns about software issues and the proposed blood-pressure capability.
- Android Central described the Ring 2 as a subscription-free Oura alternative while criticizing app polish and noting that some planned features were not available at the time of its review.
- Tech Advisor treated ECG as a notable smart-ring differentiator but said the software still needed work.
These are reviewer experiences, not proof that every Ring 2 behaves identically. They do show why the app is as important as the sensor. A useful ECG feature must start a recording, maintain contact, produce an interpretable result and preserve the history reliably.
Is the Circular Ring 2 a medical device?
No—not as a complete product, according to Circular’s own support documentation. Its support page says the Circular Ring 2 is not classified as a medical device.
Rank #4
- [Sleep Apnea Monitoring] RingConn Gen 2 Smart Ring supports sleep health with advanced technology. Developed with leading universities and hospitals, this AI-powered ring accurately tracks sleep apnea. Unlike traditional devices, it's lightweight and comfortable, offering multi-day monitoring with real-time AHI data and personalized insights via a dedicated app for easy sleep health management
- [Size Before You Buy] RingConn Gen 2 Smart Ring uses unique sizing standards, different from U.S. and other health rings. RingConn Gen 2 Sizing Kit helps you find the most comfortable and accurate fit for your finger, preventing the inconvenience of returns and exchanges by ensuring you select the correct size before purchasing
- [No Subscription Fees] Unlock lifetime access to the comprehensive suite of features on the RingConn Smart Health Monitoring App with your RingConn Gen 2 Smart Ring. Experience continuous, real-time health tracking and personalized insights
- [More Than Just Health Monitoring] RingConn Gen 2 Smart Ring surpasses standard health monitoring features by not only tracking your activity, sleep, stress, heart rate, HRV, and blood oxygen saturation but also supporting OTA updates. This ensures continuous improvements and the addition of new features, delivering an ever-evolving experience tailored to your needs
- [Waterproof for Every Adventure] RingConn Gen 2 Smart Ring features upgraded water resistance of up to 100m, making it perfect for daily wear, workouts, and swimming. Plus, RingConn Gen 2 offers outstanding durability with a gentle touch, even for sensitive skin
That means readers should not describe it as FDA-approved, FDA-cleared or a clinical replacement for an ECG unless a specific regulatory authorization is independently verified. Terms such as “clinical-level,” “medical-grade” or “validated” in marketing material do not by themselves establish regulatory status. The FDA explains how authorized sensor-based digital-health devices are identified.
Seek urgent medical care for new chest pain, fainting, severe breathlessness or severe or persistent palpitations, regardless of what the ring reports.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Who should consider it?
The Ring 2 makes the most sense for someone who specifically wants ECG capability in a lightweight, screenless ring and values subscription-free core tracking. It may also appeal to people who prioritize sleep wearability over the notifications and display of a smartwatch.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
It is a weaker choice for anyone seeking a clinically equivalent diagnostic device, guaranteed real-time emergency monitoring or a highly mature health-data ecosystem. A smartwatch may be better if you need immediate on-screen alerts, easier ECG interaction, emergency features or established integration with your phone’s health platform. Apple Watch, Samsung Galaxy Watch and other ECG-capable watches have different regulatory, battery and comfort trade-offs.
Best Value
- [AI-Powered Health Insights] RingConn Gen 2 Air Smart Ring integrates AI with multi-sensor data to continuously track key health metrics like sleep, heart rate, stress levels, blood oxygen, physical activity, and menstrual cycles. Its built-in AI assistant delivers your personalized report and guidance to enhance your wellness and daily habits
- [Size Before You Buy] RingConn Gen 2 Air uses unique sizing standards, different from standard ring sizes. Purchase RingConn Sizing Kit to find the most accurate and comfortable fit for your finger
- [No-Feel Wearing] Experience a comfortable, stylish design with a super-thin 2mm profile and only 2.5g weight. Won't interfere with your movement whether you're working out, running, diving, or engaging in any physical activity, and stays comfortable without distracting you when sleeping or working
- [No Subscription Fee for Standard Features] Unlock the lifetime use of essential standard features on the RingConn Smart Health Monitoring App with your RingConn Gen 2 Air Smart Ring. Experience continuous, real-time health tracking and personalized insights
- [Longer Battery Life] Enjoy up to 10 days of uninterrupted power with a single full charge that completes in just 90 minutes. Stay powered through your busy schedule without frequent recharging and efficiently maintaining continuous long-term data collection
Compared with other rings, Oura offers a more established sleep and recovery ecosystem but uses a membership model for important features. Samsung Galaxy Ring is relevant to users invested in Samsung Health, while RingConn is another subscription-free alternative focused more on general wellness tracking. Neither should be assumed to offer the same built-in ECG capability without checking its current specifications.
Buying checks before ordering
- Confirm the current price, stock, delivery estimate and supported country.
- Use Circular’s sizing process carefully; a smart ring cannot be adjusted like a conventional ring.
- Check which ECG and Heart Rhythm functions are available in the current app version.
- Review the current return and warranty terms. Circular’s captured product-page information listed a 14-day return period and one-year warranty, but policies can change.
- Decide whether a failed recording, synchronization problem or delayed feature would be acceptable for your use case.
Verdict
The Circular Ring 2’s ECG is a legitimate hardware differentiator: Circular announced it with a single-lead ECG sensor built into the ring, not merely as a software promise. The feature could make the Ring 2 appealing to buyers who want occasional rhythm checks in a screenless form factor without paying for a subscription.
But the right description is an ECG-capable consumer smart ring with heart-rhythm and AFib-oriented analysis—not a hospital ECG, a guaranteed diagnostic device or a substitute for medical care. The Ring 2’s value depends heavily on app reliability, fit, software updates and the availability of promised features. Buy it for convenient wellness and rhythm monitoring, not for clinical certainty.
Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Quick Recap
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.
