The HP PS/2 2-Button Optical Scroll Mouse is a two-button mouse with scroll wheel that provides the speed and accuracy of optical tracking in a simple, elegant design. It records motion precisely on a variety of surfaces using the latest optical sensing technology. The HP PS/2 2-Button Optical Scroll Mouse has no ball or moving parts, which improves its durability, makes it require less cleaning, and eliminates sticking. The mouse's comfortable, contoured shape fits either hand.