Ergonomic, ambidextrous contour trackball mouse design; Adjustable leg stands from 0? to 10? for personalized comfort; Built-in 1.5 in. large trackball with optical sensor; Removable trackball allows for easy cleaning; 7 buttons–forward, backward, left, right, scroll wheel, and DPI up/down; 400 to 4800 DPI range; 2.4 GHz wireless USB nano receiver with up to 30 ft. range; Power on/off switch; 10-million-click life cycle, durable microswitch; Includes USB receiver, 2 AAA batteries, and quick-start guide;