If you're looking for a simple way to transition from a mouse to a trackball, trust the Orbit® Optical Trackball. It offers better ergonomics, with less wrist and hand movement to ease repetitive-stress injuries. Optical tracking technology delivers precise cursor control and the two-button design provides a familiar experience for mouse converts. Medium 40 mm ball is designed as a perfect sphere to provide exceptional precision. Compact footprint takes up less desk space than you'd need to operate a mouse. Ambidextrous design works equally well for both right-handed and left-handed users. Plug & Play installation via wired USB connection. KensingtonWorks™ software lets you customize the 2 buttons, adjust cursor speed.