TRACKBALL COMFORT - Equipped with a 34mm trackball, you will not need to mouse around to move the cursor as thumb controlled trackball stays in one place. Not only work on flat surfaces, but also on your leg, sofa and other surfaces as well. A full control of everything is within your fingers. ERGONOMIC DESIGN - Places your hand in a natural wrist & arm position for smoother movement and less muscle tension. Comfortable finger rests just fit in the palm of your hand. No driver required. Once you get used to it, you will love it!