Knot Conical Brushes are for heavy-duty use, for the preparing of metal surfaces before painting, & the removal of slag, rust, scale, or concrete waste. The special shape of the conical brushes enables the user to work in hard to reach places. The Knots are left hand twisted to increase stability. Diameter. 100 mm. Width. 10 mm. Bore. M14. Wire Gauge. 0.35. Wire Type. Steel. Max R. P. M. 12, 500.