Evoluent VerticalMouse 4 Right Avoids forearm twisting for comfort and good health* The patented shape supports your hand in an upright neutral posture that generally avoids forearm twisting. Many users, including medical doctors, ergonomists and physical therapists, said the Evoluent VerticalMouse provides superior comfort and even relieved their wrist pain.* Comfortable and easy to use The shape is thoughtfully sculpted for uncompromised comfort and easy-to-reach programmable buttons. No finger contortions are needed to operate the buttons. Adjustable optical sensor Pointer speed controls on the side allow convenient adjustment without even releasing your grip from the mouse. Improved thumb rest The thumb rest has been reshaped to provide even more comfort over earlier versions. Pointer speed indicators Top mounted LEDs show through the chrome thumb rest to indicate selected pointer speed including extra low (XL), low (LO), MD (medium), to high (HI). Now two thumb buttons A new bottom thumb button provides greatly extended functionality when used with the included driver. Lighted Evoluent logo The logo is pure eye candy. The illumination turns off when the system is in sleep mode to conserve notebook battery power. Extended lip prevents rubbing An extra wide lip along the bottom edge prevents the last finger from rubbing the desk. Powerful and intuitive driver Evoluent Mouse Manager for Windows provides extensive but easy to use functionality for 6 buttons through a simple and intuitive interface. Compatibility Windows Downloadable driver for Windows XP, Vista and Win 7 in 32/64 bit for programming all 6 buttons. The driver is not required. The VerticalMouse 4 still has basic functionality without it. Freeware driver for other Windows versions USB only; not compatible with PS2 adapters. May be compatible with some USB KVM switches but it is not guaranteed. Mac Downloadable driver for programming 6 buttons. The driver is not required. VerticalMouse 4 still has basic functionality if the driver is not installed. Linux Basic functionality without a driver. Unix Compatibility unknown.