iogear GKM581R is a 2.4GHz wireless on-lap keyboard with an optical trackball and scroll wheel. It is compatible with Windows XP, Vista, 7, and Mac OS X v10.3.9 or later. The keyboard has a range of up to 30 feet and features a variety of multimedia keys, including play/pause, stop, previous track, next track, mute, volume down, and volume up. The optical trackball provides precise cursor control, and the scroll wheel makes it easy to navigate through documents and web pages. The keyboard also has a rapid fire/normal mode switch, which allows you to choose between single-click and rapid-fire modes. The iogear GKM581R is a versatile and feature-rich keyboard that is perfect for use with laptops, desktops, and home theater PCs.