Take full advantage of Trackball Optical! ??Microsoft brings the superior precision and durability technology of IntelliEye to trackballs and offers the Trackball Optical that features a comfortable ball located on the side for thumb use.??The trackball utilizes USB connections to offer instant plug-and-play action. In addition, it is the first trackball to offer five customizable buttons, including the popular scrolling wheel. Each button can be programmed for common tasks such as moving forward or backward in a Web browser or cutting, pasting and printing in Windows operating system-based programs.