About this item Optical tracking technology provides precise cursor movement for superior accuracy so you can get where you want on the screen Quickly with less hand movement, improving productivity and efficiency; The blue 40mm ball has been specially designed with an absolute spherical, hard surface for precise tracking and control Unique scroll Ring let you move up and down web pages or documents with ease; ambidextrous design works equally well for both right-handed and left-handed users Detachable Wrist rest softly cushions and cradles the hand and wrist in an ergono position for pain-free productivity during extended periods of activity on the computer Free downloadable KensingtonWorks provides a personalized experience, giving you the ability to ign a wide variety of program functions to each of the 2 buttons, as well as adjusting cursor and scrolling speeds ChromeOS user can get HID functions for a trackball but will not be able to customize their device through KensingtonWorks.