Evoluent VerticalMouse 2 Left Hand is an ergonomic mouse designed for use by individuals with carpal tunnel syndrom or repetitive strain injuries. The vertical shape of this mouse supports the user's left hand in a fully upright handshake position that eliminates twisting of the forearm. The optical sensor has 1,200 dots-per-inch (dpi) resolution, allowing the pointer to be moved across a 17-inch monitor with only 0.5 inch movement of the mouse. The mouse has five buttons that have basic functionality in Windows without a driver: left click (top), right click (middle), back (bottom), middle click (wheel), forward (thumb). A driver is included allowing each of the five buttons to be programmed with different functions in Windows XP or Vista 32-bit. Other special features when used with XP Pro and Vista 32-bit include speed toggle, auto click, click lock, and audio and/or visual break reminders. COMPATIBILITY: For use on IBM and compatible, Macintosh, Unix (except Solaris 9), and Linux-based computers. SYSTEM REQUIREMENTS: Personal computers (PCs) require USB or PS/2 port; Windows 2000, XP, Vista, or 7 operating system. Macintosh requires OX 9 or OS X operating system and a USB port. Unix and Linux require a USB port. DIMENSIONS (HxLxW): 3 x 4.6 x 3 inches. Cable is 6.6 feet long. COLOR: Silver and black.