HP 27 MHz Wireless Optical Mouse (Blue) Compact, ergonomically comfortable wireless mouse in blue with green LED and contoured edges--great for use at home and on the road Adjustable sensitivity from 1250 to 1750 cpi for maximum workability on a variety of surfaces Three buttons: two primary buttons and clickable scroll wheel Connects to PCs via USB mini receiver (27 MHz) Compatible with Microsoft Windows 2000, XP, Vista, and 7 operating systems