Wireless ring mouse: Mini mouse with an optical sensor of 800 dpi that fits on the index finger. This mouse uses wireless radio waves and is compatible with Windows ME/2000/XP/Vista, Mac OS X 10.2 and higher, and Linux (also suitable for Ultra Mobile). It features a USB 2.0 connection. Simply insert the ring attached to the mouse onto your finger, plug the USB dongle into your computer, and you can immediately use your wireless ring mouse. The left square with the small red ball (scroller) is used to move the mouse around the screen. The two bottom squares function as "Right Click" and "Left Click" on a traditional mouse, while the square at the top right allows you to scroll with a single press.