Lessmann LES487217 Knot Cup Brush 125mm M14x2.0 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. Stability bridle fitted. Diameter. 125mm. Bore. M14. Wire Gauge. 0.50. Wire Type. Steel. Max. R.P.M. 6,500.