Knot Wire Cup is for use in tight operations, corners and angle welds, curved surfaces, and pipe bevel cleaning. Double-row brush is for aggressive action in severe applications. Bristle Type / Knotted Wire Brush Dia. / 4 in Mounting Type / Arbor Hole Arbor Hole Size / 5/8"-11 Abrasive Shank Size / No Shank Wire Dia. / 0.020 in Bristle Trim Length / 1 in Abrasive Material / Carbon Steel Max. RPM / 9000