For lighter duty surface cleaning a crimped style cup brush is appropriate. Crimped wire is less rigid than knotted and can get into crevices more easily. Milwaukee offers a full range of crimp and knotted wire cup brushes. This crimp wire cup brush is designed to be used on 4-1/2 or 5 in Milwaukee and competitive grinders with 5/8-11 threaded spindles. Made from carbon steel wire.