Specifications Hign-concerned Chemical:None Waterproof Grade:None Model Number:R20 Display screen:No NFC Support:Yes Activity Tracked:Activity Tracker,Steps Tracker,Distance Tracker,Calorie Tracker Metrics measured:Heart Rate Monitor,Blood Pressure Monitor,Sleep Monitor,Blood Oxygen Monitor Item Weight:3.8g Case Material:Ceramic Certification:ce Battery Capacity(mAh):20mAh Color:Black App:Smart Health Type:Smart Ring For Men Women Type 2:NFC Access Control Smart Ring Main Function:NFC access control,heart rate monitor,blood pressure monitor,blood oxygen monitor,sleep monitor How to choose your size - Measuring Finger Method Step 1: When measuring,please choose a thin,non-stretchy wire and wrap it around your finger and mark it with a pen or other tool. Step 2 : Straighten the thin wire and measure its length with a ruler and shop against the ring specifications bove. Warm Reminder : Typically, sizes 7-8 are suitable for women and 9-12 are suitable for most men's sizes. Please measure your finger size before purchasing to avoid inappropriate size Bullet Points: 1.Supoort NFC Smart Access Control 2.Extremely thin and light. 7MM ultra thin technology, Fashion ceramic sheel , weight only 3.8g. 3.Health Check: Track your body temperature, sleep quality, and more with this multi-functional smart ring. Keep a close eye on your well-being and stay on top of your health at all times. 4.Travel-friendly Design: With its portable design, compact size, and light weight, this smart ring is easy to carry and ideal for travelers who want to stay connected and secure. 5.Surprising Gift: Surprise your loved ones with a stylish and versatile smart ring that provides universal device compatibility and convenience. This practical gift is ideal for family, friends or colleagues, and perfect for any occasion, including birthdays, anniversaries, Thanksgiving, Christmas, Hanukkah or Valentine's Day. Product Parameters: CPU: AC6323 Waterproof Level : IP68 Waterproof APP : Smart Health Bluetooth Version:BLE 5.0. Battery capacity: 20mAh. Stanby Time:About 7-10days. Working Time:About 3-5days. Charing time:1-2H. G Sensor:SC7A20H Heart Rate Sensor: Goodix GH3018 Magnet Cable(With SMT Protect IC). Charging Requirement:Charging 1A or less. system requirements:android6.0+ / ios11.0+. Main Function: Heart rate detection. Blood oxygen monitor. Blood pressure monitor Remote photography. Sleep detection (Sleep time ,Sleep quality). Multiple sports modes. Step count. Calories. Synchronous data to APK/APP. Warm tips Waterproof: It is just life waterproof. It is not allowed to soak the smartring in water! (Please be careful to avoid corrosive liquids like hand sanitizer, soap enter the smart ring and cause component damage.)