Voscale 2.4Ghz Wireless Mobile Optical Mouse with 6 Buttons, 3 DPI Levels with USB Wireless Receiver Batteries are NOT included and they are to be purchased separately. Please make sure to insert the battery in the right "+" and "-" position and also ensure that the betteries are new. 3D Buttons (left, right and scroll wheel buttons). Compatible with Window 98/2000/NT/ME/XP/win7/Win8; No driver needed, plug and play. 3 adjustable DPI levels (800/1200/1600) Note: the USB receiver is inserted in the back of the mouse. Adopt the 2.4G frequency technology, working distance can reach to 8M-10M. 2.4G will give you a more comfortable, convenient and exact effect than the traditional FM radio wireless mouse. Next/Previous buttons provide convenience while web browsing; Soft rubber grip and contoured body deliver continuous, all-day comfort. Infrared technology ensures smooth track over a variety of surfaces. Tiny USB receiver occupies minimal space when attached to your computer. 1-year limited hardware warranty