Kensington Expert Trackball Mouse (K64325) Large ball is designed as a perfect sphere to provide exceptional precision; Diamond Eye optical tracking technology for premium cursor control and accuracy Award-winning Scroll Ring lets you scan up and down pages with ease; Detachable wrist rest supports hand and wrist for ergonomic comfort Ambidextrous design works equally well for both right-handed and left-handed users Trackball Works software lets you customize all 4 buttons, adjust cursor speed Auto-sleep helps conserve AA battery life; Compatibility: Mac OS 10.8 and above; Windows 10, 8.1, 8, 7; Chrome OS 44 and above