Conical felt bobs are made of 100% wool felt, mounted on 3/32″, 1/8″ or 1/4″ shanks. These bobs are ideal for use on die grinders, electric drills and air drills. The maximum operating speed is 15000rpm. Conical felt bobs can be used with various polishing compounds or rouges to produce a clean, high finish on molds, dies, models, all metals, plastics, glass or crystal. Great for polishing and buffing all hard to reach surfaces. Three densities are available which include soft, medium and hard.