M3 water proof smart fitness band is a 3 in 1 Monitor with a heart rate machine .It is compatible to devices having Bluetooth version 4.0 and below in smart phones, Tablets and PC's and also support Android and IOS.Please refer the manual received with the box and scan the QR code for the app to be installed. Smart Band keeps you connected wherever you go!! Features like Check the current time,Record your steps SMS Bluetooth Sync Reminders, SMS Notifications Stand by time: 300 hours Calories: Calories of sports Heart Rate Sensor: Check your heart rate ,Pedometer: Sports Pedometer, Motion Odometer Sleep Monitor: At night, check the quality of sleep in APP. Heart Rate & Sleep Monitoring: It learns your activity level including amount of steps, mileage, heart rate, and records calories burned throughout the day, improve your overall wellness today, tomorrow and well into your future Tracks real-time heart rate automatically & continuously and automatically tracks your sleep duration & consistency with comprehensive analysis of sleep quality data, helping you adjust yourself for a healthier lifestyle. Built-in USB Plug: Built-in USB plug makes it easy to charge with any USB block and computer; no charging cable and dock needed; Full charge requires only about 1-2 hours and gives you up to 7 days of working time.Battery Capacity and Battery Type: 90mAh Polymer Rechargeable Lithium. How to charge?This fitness tracker has a built-in USB port, please separate the device from strap and and insert the USB charging plug into normal DC USB port (5V-500mA). The "Charging" will be light on while right charging, if not, please check and turn the device's USB charging plug to the correct direction, or try another socket.Warm tips: To ensure the lifespan of the device, please remove the device host from the power supply once fully charged. It takes about 1~2 hours to have the host fully charged.