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. Ref: UTTK2554