These hones are fantastic for many different applications. Most notably for reaming out (and straightening) the holes in perfume bottles and leaving an excellent angled taper in the hole. The shanks are turned from steel and plated on the tips with a 150 grit diamond. They perform very nicely under heavy usage. Always use with water when grinding. With proper care they should provide a quick and easy solution for mating stoppers with perfumers. Can be run in either a hand held drill (cordless even) or in a drill press.