Lenovo 400 Wireless Mouse GY50R91293 Nano USB provides strong 2.4 GHz wireless connection Responsive and clear tracking with 1200 DPI resolution optical sensor Up to 8 million clicks for left and right buttons Comfortable and functional in left or right hand Lightweight for travel at 65 g (2.29 oz) Battery life lasts up to 12 months(may vary based on usage)