3mm Brass wire brushes(CUP shape) Suitable for your Die Grinder & Rotary Machine tools. Ideal for Removing Rust/Corrosions from Any Metal Surfaces (e.g.: Steel, Aluminum, Zinc Alloy, Brass, Copper, etc.), especially Precious metals. Fit your hand drill, drill press & your Dremel® and Foredom®tool with a 1/8"collet. Perfect Accessories for Jewelers, Locksmiths, Gunsmith,Technicians, Coin Collectors, Archeologist, Students & ect.