Contour is a family of ergonomically shaped mice that supports every hand regardless of size. This allows your grip on the mouse to be relaxed, helping you avoid excessive bending of your fingers. The Contour Mouse features five buttons, including a full-sized third button in the center. The three primary buttons are extra long, enabling you to click with small, gentle movements using outstretched fingers. Your thumb rests between the forward/backward button and the scroll wheel on the side of the Contour Mouse. Your hand should rest on top of the Contour Mouse, providing support for the entire palm. To find the right size for the Contour Mouse, measure the length of your hand from the tip of your middle finger to the first crease of your wrist.