1. Choose the size and fully charge before purchase and use Choose the most suitable size from a range of sizes between ring size 7 and 12. Please make sure the smart ring is fully charged before use so that it can be successfully linked to the mobile phone APP, because it has been in a power-off state in the Amazon warehouse for dozens of days. 2. Comprehensive health monitoring fitness tracker ring can not only monitor heart rate, blood oxygen saturation, but also record steps, distance, calorie consumption, and has multiple sports modes. 3. Long battery life The 18mAh battery combined with an efficient battery management system can make this smart ring health tracker work for up to seven days, but it only takes two hours to fully charge. 4. 5ATM waterproof and remote photo control Don't worry when it rains or swims. The waterproof smart ring has a 5ATM waterproof rating. After enabling the remote photo function on the app, you can take photos remotely by simply shaking the finger wearing the ring.