The Apple Pro Mouse has no rollers or tracking mechanisms to wear out or clog, and no mouse balls to fish out and clean. Besides all that, there's no distinguishable mouse button. Instead, the entire Apple Pro Mouse is in effect a super-sensitive button - the body pivots up and down to actuate the click mechanism. It even lets you fine-tune the way it clicks, with user-adjustable click tension. The elliptical shape equally accommodates right and left-handed users, and its glass-smooth surface makes it a joy to use.