Note: When you use the Mi band， you must download the APP.Features:Heart rate monitor: with optical heart rate sensor， shows you heart rate with PPG， you can see the results more intuitively30 days standby time: Top-level Bluetooth chip and military gravity sensor ensure 30 days ultra-long standby time for a full chargingCall reminder: it will tell you when a call comes， you never need to worry about missing any important callsSports tracking: Track your sports， record steps， distance and calories， help you achieve your sports targetSleep monitoring: Let you know your deep sleep and shallow sleep， also APP will give you periodical evaluation， help you develop good living habitsSilent alarm: Wake you up every morning， will not be late for work; Remind you with vibration， never worry about missing anything.Free password to unlock the phone: Forget complex unlock password and gesture， simply raise your hand to close to phones， immediate and safe unlockingSupports Android 4.4 or above， bluetooth V4.0 Android cell phones， suitable for iPhone 4S/5/5C/5S/6/6plus/6s/6s plus with iOS 7.0 or aboveSpecifications:Battery Capacity: 45mAhInput Current: 25mAInput Voltage: DC 5.0VBluetooth: 4.0Metal Surface Material: Full magnesium-alloyWristband Material: Dow Corning TPSIVBody shell: PolycarbonateWaterproof Rate: IP67Wristband Color: BlackAdjustable Wristband Length: Approx. 157-205mm/ 6.18-8.07"Package Included:1 x Tracker1 x Wrist Band1 x USB Charging Cable