The Expert Mouse® Wired Trackball is the productivity enhancer professionals use to get more work done in less time. It offers highly accurate cursor control and great comfort for your hand and wrist. TrackballWorks™ software can customize the four buttons, and the Scroll Ring lets you quickly scan up and down your screen. KensingtonWorks™ lets you customize all four buttons, set cursor speed. DiamondEye™ optical tracking technology for premium cursor control and accuracy. Award-winning Scroll Ring lets you scan up and down pages with ease. Large 55 mm ball is designed as a perfect sphere to provide exceptional precision. Detachable wrist rest supports hand and wrist for ergonomic comfort. Reliable wired USB connection. Kensington worked directly with Microsoft to provide professional-level solutions that look as good as they function, so you can work like a pro.