Circular Ring 2
A Kickstarter-funded titanium smart ring with FDA-cleared ECG – from a company now in judicial liquidation.
$379.00 USD
Available
Image: Circular
Overview
The Circular Ring 2 is a titanium smart ring that raised $4 million on Kickstarter promising FDA-cleared ECG, blood pressure monitoring, and glucose trend tracking without subscriptions. Independent investigation revealed it is a white-labeled Linktop Cardio Ring. The company entered judicial liquidation in October 2025, leaving 13,000 backers with no customer support, no refunds, and unfulfilled feature promises.
Key Features
- FDA-cleared ECG with AFib detection
- Titanium construction with IP68 water resistance
- Digital smartphone-based sizing (no sizing kit)
- No subscription for core features
- PPG heart rate, SpO2, skin temperature sensors
Description
The Circular Ring 2 is a titanium smart ring featuring an ECG sensor with FDA-cleared atrial fibrillation detection, PPG heart rate monitoring, SpO2 blood oxygen, skin temperature sensing, and a 3-axis accelerometer. Launched via a $4M Kickstarter campaign in March 2025, the ring promised blood pressure monitoring and blood glucose trend tracking as stretch goals – neither of which has been delivered. Independent investigation confirmed the hardware is a white-labeled Linktop Cardio Ring. Circular SAS entered judicial liquidation in October 2025.
Specifications
Battery
| Battery Life | 5-8 days |
|---|---|
| Charging | Wireless clamshell case (USB-C) |
| Charge Time | 30 min |
Connectivity
| Bluetooth | BLE |
|---|
Physical
| Material | Titanium with PVD coating |
|---|---|
| Thickness | 2.55 mm |
| Width | 7.8 mm |
| Weight | 3-5 g |
| Water Resistance | IP68 (50m) |
| Sizes | US 6-14 |
| Colors | Obsidian Black, Silver, Gold, Rose Gold |
Sensors
| ECG | Yes (FDA-cleared AFib detection) |
|---|---|
| Heart Rate | PPG optical |
| SpO2 | Yes |
| Skin Temperature | Yes |
| Accelerometer | 3-axis |
Software
| App | Circular (iOS/Android) |
|---|---|
| Subscription | No subscription for core features |