Hand-Held 4D Off-Table USB Trackball Mouse Patented design; Innovative input devices; Operating without space limitation; Plug and play, free driver; Single ball, high speed optical 4D scroll inside; 4D page scrolling function can be controlled simply by thumb; Avoid wrist and muscle injuries; Target users: Notebook PC users and long-time PC operators; Compatiblity: Windows95/98/2000/ME/XP, Windows NT, vista; Interface: PS/2 or USB connector optional; Resolution: 200 dpi; Dimention: 8cm*4cm*5cm; Length: 2.0M Shipping details: Individual Packaging Details(Inner Packing): Color box Quantity/carton: 40PCS Gross Weight: 6 kilogram Net Weight: 4.24 kilogram Master/Export Carton Volume Cu. Meter: 46x31x31cm