TOOGOO(R) Bluetooth 4.0 Smart Wrist Watch Health Bracelet Sports & Sleep Tracking Fitness-Black Material: ABS plastic, TPU rubber and alloy. Wristband longest :24cm. Wristband shortest:15cm. For android system requires Android 4.3 or later, the device supports Bluetooth 4.0. Compatibility for:Android 4.3 and its upper; IOS7.0 and its upper. Battery power 80mah. Standby time 32 hours.