Lessmann Knot Cup Brush 80mm M14x2, 0.50 Steel Wire*Knot Cup Brushes are for heavy duty use for the preparing of metal surfaces before painting, and the removal of slag, rust, scale or concrete waste. Lessmann knotted brushes are filled with a special steel wire of high tensile strength in order to meet the demands of this type of brush. Products marked with a * have a bridle fitted which an be removed to expose a further 20mm of useable wire. Diameter. 80mm Bore. M14. Wire Gauge. 0. 50. Wire Type.