The Wire Cup Brush offers a good coarse surface finish. It is fitted with knotted wire for heavy-duty cleaning applications on steel. This brush is suitable for removing heavy rust, underseal, paint or varnish. Brush wires are available in different thicknesses for variable levels of abrasive needs. Thicker wires are more aggressive, producing a coarser yet faster surface finish, while thinner wires deliver finer, smoother surface results. It is intended for use with drills with a 6-mm shank.