Brush Research's BUSC320 Single row knotted cable twist cup brushes are available in 2-3/4" diameter. Knotted cup brushes are recommended for removal of burrs, weld scale and rust, edge blending, paint removal and surface prep. Made with 0.020 carbon steel filament with a 5/8"-11 arbor hole for attachment to grinding tools. Max RPM 14,000.