Advanced trackball for scrolling and pointing Large button design for comfortable use Detachable wrist pad USB, PS/2+Serial all available Dimension: 192*119*60(L*W*H) mm Weight: 299g Compatible OS: 98 / 2000 / ME / XP Switch life: 1,000,000 cycle life Operation Voltage: +5Vdc + 5% Current consumption: max 20 mA Package type: Color box Package dimension: 243*193*43mm Pcs / carton: 20 pcs