Logitech Ergo M575S

A trackball changes what your arm does, not what your hand does. The mouse stays put and the thumb drives the cursor, so the repeated sweep across the desk disappears entirely. That is the whole argument, and it is why people with cramped desks and people with shoulder complaints arrive here from opposite directions.

The adjustment is shorter than the one a vertical mouse demands. Owner reports describe a few days of overshooting targets and then normal speed, with fine positioning — dragging a corner handle, selecting four characters of text — staying slightly worse permanently. In documents and browsers that costs nothing. In photo retouching it is a real loss.

Maintenance is the part the listing never mentions. Skin oil and dust collect on the three bearings the ball rides on, and the cursor starts stuttering weeks before you work out why. The ball pushes out through a hole in the base and the bearings wipe clean in seconds, but the ritual needs doing every few weeks forever. Third-party balls in the same size fit, and some owners swap them in for a smoother roll.

The S revision is a quiet one. The ball colour changed and the packaging was refreshed; the shell, the sensor, and the tilt are what they were. Nobody who already owns the earlier version has a reason to replace it, and both are still on the shelf, which mostly creates confusion at the point of purchase.

Two device pairings, not three. The Master line switches between three machines and this switches between two, which sounds trivial until you have a work laptop, a personal one, and a tablet. There is no Flow either, so moving between machines means reaching for the button underneath.

The tilt is fixed and mild. This is not a vertical mouse and does not pretend to be one, so the forearm sits in roughly the same rotation a conventional mouse forces. If pronation is the specific thing that hurts you, a trackball is solving a different problem than the one you have.