A4Tech Wired Ball Mouse SWW35. Device interface: USB+PS/2, Movement detection technology: Mechanical, Movement resolution: 520 DPI. Compatible operating systems: Windows 95, 98, Me, NT 4.0, 2000, XP Mac OS 8.5 - 9.X, Mouse dimensions (WxDxH): 6.9 x 12.4 x 3.8 mm