Off-table, for free and comfortable operation. Can be operated in various ways, avoiding harm to palm joint or muscle. * High accuracy and sensation. Can be used on the surface as same as optical mouse. User doesn"t have to sit close to the monitor by using this track mouse; * Avoiding eye fatigue and radiation harm. Can control the cross coordinates sensitively, simply with the thumb. * Compatible with: Windows98, 2000, XP, VISTA, win 7, Linux, Unix, Mac OS * Package includes: 1 x Wire Trackball Mouse, 1 x Receiver, 1 x Cable, 1 x Bag