Proxxon 28304  0 7/8-Inch Silicon Carbide Grinding Wheels, 10-Piece Silicon grinding wheels use for stationary or free-hand grinding and sharpening Good for use with hard materials such as cast iron, unhardened steels, non-ferrous metals, hard metal alloys, welded joints, rivets and rust Good for use with Proxxon's precision rotary tools or other name brand rotary tools