4" .020 wire cup brush. Use on angle grinder for fast removal of heavy rust, corrosion, weld scale and spatter. Use to clean weld beads, angle weld and corners in tight places. For roughening, deburring and surface cleaning prior to welding. Wire size .020". 5/8" - 11 UNC arbor hole. Diameter: 4", Wire Size: 0.02", Wire Style: Knotted, Maximum Speed: 9000 RPM No. 36045: Diameter: 6", Wire Size: 0.02", Wire Style: Knotted, Maximum Speed: 6000 RPM