Optical, USB 2.0 (compatible with USB 1.1) mouse Touch-sensitive technology concealed under the seamless top shell, you get the programability of a four-button mouse in a single-button design Force-sensing side buttons Revolutionary 360 degree Scroll Ball lets you move anywhere inside a document, without lifting a finger Compatible with Mac OS X (programmability requires Mac OS X v10.4.2 Tiger or later), or Windows 2000 or Windows XP