Easy to mount/replacement with the shaft.Cup type brush which is easy to operate due to compact and high speed rotation, excellent in usability.Since it is cup type, it is optimum for bottom/curved surface corner grinding.Optimum for polishing flat and side surfaces.Working Tool: Variable speed type electric micro grinder.Wire Diameter (mm):0.30Bristle Material:Abrasive Grain Nylon #320Outer Diameter x Bristle Length x Shaft Length x Shaft Diameter (mm):13 x 8 x 40 x 3Max Working Rotation Speed (rpm):10000Comments:Inner diameter polishing, burring, black layer removing of various metal products.Shaft: Free-Cutting Steel