GMYLE(TM) Black Wired Ergonomic Handheld 2.4GHz USB 2.0 Trackball Mouse for Windows XP/Vista / 7 / Mac OS with Multi DPI No need the table. Off-table use. Plug and play, no software required. Fast and accurate cursor movement 4 groups adjustable DPI including 400,600,800,1200 Left and right hand design. Reduce the wrist pain. Help prevent Musculo-Skeletal Disorders Cable length 2 meters No operation space restriction, which is also suitable and convenient for living room multimedia center, convenient button control let you able to operate when youre setting, leaning, lying down or other body posture.