Key Features  520 dpi, 30% faster than most others 5-button (left + right + 2-side +  wheel button) + 2-wheel No tracking ball to clean Precision optical sensor Advanced design with 5 programmable buttons Works on most surface Valued iWheelWorks program included  Zoom in/out and auto-scroll in Office 97/2000 Windows 95/98/Me/NT/2000 multilingual driver included Specifications Model: O-35G (Gift Box) Interface Protocol: PS/2 Current Consumption: 15mA max@5.25V Mass weight (with cable): 109g Switch Life: 1,000,000 cycles Button: 5 buttons Cable Length: 160 cm  Electrical MTBF: 150,000 hrs Mouse Resolution:  520 dpi Mechanical Life: 500 miles Operating Systems: Windows 95/98/Me/NT/2000 and beyond. Certifications: FCC Class B, CE, C-Tick