The HP 3-Button Optical USB (Universal Serial Bus) Mouse is an ambidextrous (for right & left handed use) three-button optical mouse that plugs into a USB (Universal Serial Bus) port. Its simple & elegant design is contoured to ensure the user's comfort. It uses an advanced SDNS-2599 optical sensor from Agilent Technologies. This black & gray high precision mouse glides across most surfaces, recording motion optically without a ball or rollers. Optical tracking is the latest advance in computer mouse technology. Optical mice have a tracking system that works through light which means that there are less moving parts for greater durability than ball-based mice. The optical sensor within the mouse employs a scan rate of up to 460dpi. This optical system guarantees crisp motion tracking on many types of surfaces without a mouse pad. Without a ball or roller to clog up, it works without cleaning.