1,Desktop optical metal trackball with 25mm diameter 2,Water/dust-proof ... , making it ideal for payphones, kiosks and other demanding applications- Desktop style,no mounting needed- With a slope at the front ... , 98SE, 98ME, 2000,XP• USB: Win 98SE, 98ME, 2000,XP, Mac OS9 / OSXReliability• MTBF >20000h• MTTR <30minDimension• 99.2 x 69 ... .5x 35.0 mm(LxWxH) IP65 rated 25mm Desktop Optical Metal Trackball