Abletrack is a switch adapted track ball designed for use by individuals who wear wrist splints or who have carpal tunnel syndrome, fine motor disabilities, limited hand function, or upper extremity disabilities. This track ball can be operated without the thumb or fingers as it requires no grasping, pinching, or twisting. It comes with two large, removable external hand switches which can be operated using the palm, fist, or side of the hand. The knee, foot, toes, etc. can also be used. The switches can be operated in any orientation, including upside down. When the external switches are plugged in, they perform the functions of the track ball's built-in switches. When the external switches are unplugged, the track ball can be operated normally. External switches can be affixed to a surface with tape or Velcro. The track ball uses opto-mechanical technology with variable resolution from 20 to 6,400 dots per inch (DPI)for precise control. The unit comes with three long cords, a third switch is programmable with optional software, a pearlized ball, and a removeable wrist rest. A removable retainer ring provides ease of access to the ball and rollers for cleaning. OPTIONS: External foot switch with a stiffer spring substituted for hand switch. COMPATIBILITY: For use on IBM PC AT, Macintosh, Linux, or compatible computers. SYSTEM REQUIREMENTS: Windows 9X/XP/NT/2000/2003/ME/Vista or Linux Kernel Based Operating System with HID USB mouse drivers or Mac OS 10X, USB (Universal Serial Bus) Port (1.x and 2.x compatible) or a PS/2 mouse port, 256 kilobytes RAM, and 10 megabytes hard disk space. DIMENSIONS (HxLxW): 1.75 x 5.5 x 4 5/8 inches. The wrist rest adds 2 inches to the length. The ball is 2 inches in diameter. The removable switches are 4 x 2.5 inches. The switch cords are 6 feet long and the track ball cord is 5 feet long. COLOR: Track ball is green and the body is available in black or beige. WARRANTY: 30-day money back guarantee and one-year limited warranty.