The Kensington Expert Mouse® is so much more than a mouse. It employs our DiamondEye optical technology for smooth and precise cursor control. Surrounding the ball, is an award Scroll Ring® that puts scrolling right at your fingertips letting you fly through web pages and documents. There's even a soft wrist rest included with the Expert Mouse® trackball for comfort and convenience no mouse can match. Designed for PCs and Macs and a large ball for exceptional control the Expert Mouse Optical Trackball sets the industry standard.