20pcs SIA 100mm Sanding Disc for 4 Inches Angle GrinderAluminum Oxide fiber disc for general metalworking applications For use on all metals Grinding of aluminum castings Treatment of weld seams and joints Grinding of areas Deburring and edges breaking General dressing work Dimensional stability guarantees constant cutting speed Stable edges Active additives guarantee cool grinding with virtually no discoloration of workpieces Best with mild steel, carbon steel, copper alloys, brass, bronze, aluminum