Very good product, ergonomically well designed. The + Very good glide. Free wheel or toothed choice thanks to a small button cleverly located just beneath the scroll wheel. Adjustable resolution from 400 to 1600 dpi (200 dpi hopping), a selector to the left of the index to switch mini max resolution to the resolution defined in the logociel. The - I find it a bit heavy. The shoes very quickly scratch if used directly on the desktop and slips strongly feels. So the use of a mat is strongly recommended. Too bad the resolution selector does not allow a continuous passage by jumping 200 dpi between 400 and 1600
However the overall balance is more than satisfactory.