400mAh Rechargeable Battery is Built-in. Charging 1 hour to work for 2880 hours. 10 Meters Working Distance. 2.4GHz wireless connectivity. Easy Operation: Comes with a nano receiver inside the back of the mouse. 3 adjustable DPI levels (800-1200-1600 DPI) enables you to control the speed of the wireless mouse freely. Slim & Silence Click Maybe you need to be gentle to this mini wireless mouse,it is suitable to handle by both hands based on symmetry design Care-free Warranty Any problem please contact first, quite easy to get a new one or refund,no need to return, just a email, Please!