Cordless TrackMan Optical combines smooth and precise optical tracking with reliable digital radio technology. It comes in a comfortable, sculpted shape with a soft-touch surface. Logitech's exclusive cruise control scrolling enables quick and convenient scrolling through documents. You can also easily move text and objects with simple drag-lock, without having to hold down a button while rolling the ball. The two navigation buttons enable you to move quickly between pages in applications and on the Internet. Smart power management extends battery life. Convenient button controls: Let you easily move forward and backward when you're surfing the Web. Fingertip-based control: Enables fast, accurate cursor movements. Patented Marble? optical technology: Ensures smooth tracking Cordless trackball with optical tracking system Reliable radio technology eliminates cable clutter Optical technology provides smooth, responsive performance Cruise Control buttons for easy scrolling USB connection works on PC and Mac 5-year guarantee System Requirements:PC/MAC