[AUTO ENERGY-SAVINGSLEEPING MODE]: Li-polymer batteries,high cycle life.the Auto Switch Off function will help you save energy as your bluetooth mouse will switch off when your PC is turned off or the receiver is disconnected. If you do not use the mouse for eight minutes, it will go to sleeping mode, you can press the any button to weak it up.[BUILT-IN BATTERY]: Built-in battery,easy to charge by micro usb cable,no more need for extra AAA battery.please please keep the mouse power switch in "ON" position when charging .[ERGONOMIC DESIGN] Good surface coating technology given you a skin-like touch feeling. User-friendly design provide all-day comfort for work and entertainment, portable and pocket-sized perfect for travel, Mute design keeps away annoying clicks.[Silent mode button silent]Whether you use it in a dormitory, library, or office, do nt worry about affecting others.Delivery Quantity: 1pc,Size: 21*112*56mmcolor: WhiteKind tips1. Package content: only the above package content, excluding other products.2. The size is measured manually, please allow 1-2 cm measurement error3. Due to different displays and lighting effects, the actual color of the item may be slightly different from the color shown on the picture.