Microsoft Trackball Optical Mouse, Trackball (D67-00005)

When I first got the trackball, I thought it was wonderful. My old trackball was so badly gummed up and it would only stay clean for a couple hours before I would have to open it up and clean it. This one stays clean for several days between cleanings, and only takes a few seconds to clean. You just pop out the marble with the hole on the bottom, and rub the fuzz off the bearings inside. Then pop the ball back in. Very easy, very fast. The only cons are that the extra buttons cannot be set to be duplicate "right click" pr "left click" buttons.