The Bosch M14 Knotted Wire Cup Brush is suitable for small and straight grinders as well as large grinders with a locking nut. The metal wire cup brush provides an extra-coarse surface finish. Suitable for cleaning work on medium to large steel surfaces, such as removing heavy rust, underseal, paint or varnish. The thicker the wire on the cup brush, the more coarse the result. The thinner wire will produce a finer, smoother result.