( BUILT-IN BATTERY ) :Built-in battery, easy to charge by micro usb cable, no more need for extra AAA battery. The Auto Switch Off function helps you to save energy as your cordless mouse will be in sleep mode in 15 minutes of inactivity. Best Gift for Christmas, Boxing Day, Holidays. ( WIDE COMPATIBILITY ) :Compatible with most system including Windows, Mac and Linux. Fit for Notebook, PC, Laptop, Computer and other device. ( Notice ) This mouse is compatible with the mac system that is above Mac OS X 10.10.4 and Mac OS High Sierra(No.10.13.3). ( 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.