These work great for what I got them for, sanding some brass I casted. It’s pretty much exactly what I wanted and works at a decent speed sanding away material. Unfortunately one of the rounded pieces came with no washer and a stripped screw, so it is unusable and I can’t even take it apart to add one. As these were the main shapes I bought the packages for, that was pretty disappointing and seems to indicate a lack of quality control. Otherwise, great product, and I wish I could give it more stars, but having 12% of the item be useless is a letdown.