The Firepower 1423-2108 Wire Cup Type Crimped Wire Brush has a 1/4-inch shank, a 2-1/2-inch cup diameter, 0.008-inch high quality fine tempered carbon steel wire and a 4,500 maximum RPM. Firepower wire cup brushes are designed for use on portable power tools. Firepower brushes provide fast cutting action for removal of light encrustation of scale, slag, rust, paint or weld splatter. The relative high flexibility of fire power wire cup brushes allows cleaning on irregular surfaces as well as flat surfaces. This small diameter, heavy-duty cup brush has arbor adapters and threads to fit most grinders and is designed for use in restricted or hard-to-reach areas.