LYNWO M4 Health Smart Bracelet Dynamic Heart Rate Blood Pressure Monitor Sleep Tracker Bluetooth Wristband - Black Series: Material: ABS+ PC case, TPU band OS Compatibility: Smart phones of Android 4.3 and above/iOS 7.0 and above,Bluetooth4.0 Screen Size: 0.86 Inch OLED screen,96*32dbi Bluetooth: Bluetooth 4.0 Battery Type: 180mAh Li-polymer battery Standby Time: 8 days Band width: 46.3mm*18mm*13.4mm Weight: 20g