Logitech TrackMan® Trackball (904353-0403)

This is a poor imitation of Logitech's original (and high quality) Trackman Marble Wheel. Despite using the same ball and mounting scheme, they decided that they could make this new version without a ring to remove the ball for cleaning. I loved my old Trackman, even though I had to clean it every few days; I keep my hands clean, but I used it a lo. Less than a week after I bought two of these new Trackmans--one for home and one for office--I've had to tear them open to clean them to restore the ball action to a smoother out-of-the-box feel. Another problem is that the mouse wheel and right button are badly placed and do not correspond to normal 3 button mouse finger placement like the original did. Finally, a lesser issue of taste is that the mouse wheel roll is too discrete. It's nice that it's not completely smooth and featureless, but there's a little too much resistance/feedback.