Fitness band with Bluetooth 4.0 function. Track your activity and your sleep, and get it displayed in the free app. Direct USB for charging the fitness band (full charge takes approximately 30 minutes). Easy to use, just one button on the fitness band. Intuitive app for your smartphone (Android and iPhone). Pair with your smartphone via Bluetooth. Supported devices: Android 4.3 with Bluetooth 4.0 and above, and iPhones/iPads with iOS 7.0 and above. Caller ID display and SMS notification. Pedometer function: steps, distance, and calories calculation. Self-timer and find phone function. Vibration alarm clock function. 0.49-inch OLED display. Built-in lithium-ion polymer battery: 40mAh, standby time 3-5 days.