Wired, optical, 4-button mouse with fantastic prospects. The trackball is perfectly placed for rolling 360˚: up, down, left, right and diagonally. The touch-sensitive shell detects which part of the mouse you click on so you can both right-click and left-click. The pressure-sensitive side sensors can activate Mac OS X settings such as Dashboard, Exposé and other functions. The optical tracking tracks with precision on nearly every surface. USB connection. Compatible with Mac OS X 10.4.8 or later.