High precision optical mouse. Ergonomic design. Plug and play, no-driver required. Scroll without needing scrollbars. Roll the wheel for the easiest scrolling in applications, without clicking in scrollbars. Press the wheel for the extra mouse button. Optical Tracking Engine. the optical tracking sensor accurately scans the surface of your desktop many times every second for smooth and fast cursor tracking on your computer screen. Comfortable Shape: the comfortable shape provides easy control whether you hold it with your right or left hand.