Buy this Jawbone have made UP3™ Ruby Cross so lightweight, comfortable and stylish, you’ll never want to take it off. The device tracks your steps, advanced exercise monitoring, calories burned, advanced sleep (REM/Light/Deep) and heart rate (Resting/Passive). It wirelessly syncs with compatible Apple (iPhone 4s+) and Android devices (Android 4.3) using Bluetooth 4.0 BLE. It’s splash-proof with up to 7 days of battery life. 1 year limited manufacturing warranty.