Kensington Orbit Trackball Mouse with Scroll Ring (K72337US) Trackball Mouse with Scroll Ring for comfort and precision Customizable 2-Button design via TrackballWorks software Compatible with Windows (including Windows 8) and Mac OS Computers Scroll ring allows fast, easy scrolling of web pages and documents Uses far less desk space than a mouse Optical technology for precise tracking - no cleaning required Click-free scrolling USB connectivity