This device is for polishing jewelry. I have not actually used it yet, but a friend uses one just like it. Hers arrived with the little door broken. Mine is fine, though slightly scratched. There are no instructions in English, but it is rather self-explanatory. I used to have a rock tumbler, but I could not get the cylinder to open, and the instructions warned against prying it open, lest you break the seal. I threw out the shot that came with it in favor of stainless steel shot (no rusting). I'm happy with it.