The USB (Universal Serial Bus) Optical Scroll Mouse is a two-button mouse with scroll wheel that provides the speed & accuracy of optical tracking in a simple, elegant design. It records motion precisely on a variety of surfaces using the latest optical sensing technology. It also allows scroll wheel to function as a third button. The USB (Universal Serial Bus) Optical Scroll Mouse has no ball or moving parts, which improves its durability, makes it require less cleaning, & eliminates sticking. The mouses comfortable, contoured shape fits either h&. 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 USB (Universal Serial Bus) Optical Scroll Mouse employs a scan rate of 800dpi. This optical system guarantees crisp motion tracking on many types of surfaces without a mouse pad. There is no ball or roller to clog up so it works without cleaning.