USB receiver stored at the bottom and batteries inside the mouse compartment * Over 60,000 encoding to avoid interference with other RF/wireless devices * Scroll Wheel * CPI(dpi) button for adjusting the resolution and speed of cursor movement * Ultra mini receiver for real Plug & Play in no time * Ultra-low power consumption design * Ergonomic design for both left-handed and right-handed * Power on/off button right at the mouse bottom * 2 x AAA batteries required (batteries not included) * 3 x plastic feet evenly distributed over the bottom of mouse for a smooth and free movement * Compatible with Windows 98, 2000, ME, XP, Vista, Macintosh all OS Package includes: 1x mouse L3-3/4" x W2-1/2" x H1-1/2" 1x ultra mini wireless USB receiver stored beneath the mouse  (less)