The logitech marbke trackman trackballs are great. I have been purchasing this brand of trackball for the last ten years. My ten yr.

Computer cursor interface requires less strain on the wrists than a traditional mouse. It reacts quicker and doesn't require the space a mouse does. One has to learn to scroll with the keyboard because of the lack of a scroll wheel.

It cannot be programmed to simulate the apple mouse's scrolling feature. And those little * on the side are almost useless.

The trackball is too small and requires at least twice the rotations in order to move the pointer across my monitors. It jumps, it skips, it drifts.

It's not comfortable, not as intuitive, and much harder to use. It requires an even more unnatural hand position than a traditional mouse. It's sticky and jerky.

Only this mouse gives problems and crashes setpoint. It freezes! I have a touch pad, so every time it freeze, i move on the touch pad to check whether it is freezed because of the mouse.

Used this seller because i thought i would be receiving the higher quality older model from logitech. It has a horrible scratchy, cheapo plastic feel instead of the smooth feel of the old version.