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. It is intended for use with drills with a 6-mm shank. 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.