YUEHISY Smart Health Tracker - 8 ID: 18.1mm/0.711in, Circumference: 56.9mm/2.24in

Specification: Item Type: Smart Ring​ Material: Epoxide Resin, Stainless Steel (Cloisonne Enamel Finish Craft) Ring​ Battery Type: Li Battery (Included) Battery Capacity: 20mAh Charging Case Battery Type: Li Battery (Included) Battery Capacity: 200mAh Charging Method: Magnetic Charging Waterproofing Level: IP68 Bluetooth​ Version: 5.0 Compatible System: Support for Android 5.1 (and above), Support for IOS 8.0 (and above) Charging Time: 1-2 Hours Standby Time: 7-10 Days Working Time: 3-5 Days How to Use: Download the instruction manual APP to operate. PackageList: 1 x Ring​ 1 x Charging Cable 1 x Charging Case 1 x Manual Note: The size can be selected based on the inner diameter circumference.