Fitness Activity and Sleep Tracker Wireless Wristband, Slate, Large Function: Pedometer/Calorie counter/Distance counter/anti-lost/Sleep monitor/stopwatch/Incoming call alarm/SMS reminder/Email reminder Main Material: Texture Germany TPU - Display: Come with a 0.49 inch OLED screen Waterproof, slim, comfortable and easy to wear. Big Size: 6.3-8.2 inch (161-209mm) Wear all day and night - even in the shower. Battery: Rechargeable Lithium battery.