... polishing, and removing scale, rust, corrosion. twist knot cup brush,Heavy-duty cleaning of large metal surfaces.weld scale and ... and 0.50mmRPM:12,500Steel wire type:brass-plated steel wire,phosphated steel wire,galvanized steel wire and steel cordBowl type:galvanized ... jobs and for brushing large surfaces with good balanceOther diameters:65,75,85,90,100 and 125mm 4" cup brush with crimped wire