Specifications Hign-concerned Chemical:None Waterproof Grade:5ATM Model Number: R02 Display screen:No NFC Support:No Activity Tracked:Activity Tracker,Steps Tracker,Distance Tracker,Calorie Tracker Metrics measured:Heart Rate Monitor,Sleep Monitor,Blood Oxygen Monitor,Stress Monitor Item Weight:4.7g Case Material:STEEL Certification:ce,FCC Brand Name: Battery Capacity(mAh):17mAh : No.1 in sales smart ring on AliExpress, and is far ahead. Note: 1. For best performance and accuracy, we recommend wearing the Ring on your index finger. If you prefer other fingers, the middle and ring fingers are also OK. Avoid using fingers that are narrower than the knuckles at the base. 2. The size of rings may not be completely in line with universal standards. Please measure your finger circumference before purchasing and make sure it fits comfortably, then choose the appropriate size. 3. How to start: Charge the Ring with the included charging cable. The heart rate light will light up to indicate successful startup. Then you can use the APP Qring to connect the Ring. Smart Ring - R02 Introducing the revolutionary R02 Smart Ring a breakthrough in wearable technology, offering seamless health monitoring right at your fingertips. With its state-of-the-art design, you can effortlessly track your heart rate, blood oxygen and stress levels all without lifting a finger. Your health data is automatically recorded, ensuring you're always in the know about your body's status. Wear it worry-free every day, the titanium steel shell, paired with advanced low-temperature potting technology, grants the ring a 3ATM&IP68 water resistance rating. the R02 Smart Ring is not just feather-light but incredibly durable and resistant to wear. Its ruggedness is matched by monitoring accuracy, with 20 different exercise modes that monitor your heart rate data in real time during exercise. Embrace the future of smart wearables with the R02 Smart Ring a perfect blend of innovation, style, and health consciousness.