Flap Disc, Abrasive Type Coated, Abrasive Material Aluminum Oxide, Grade Coarse, Backing Plate Material Fiberglass, Connector Size 5/8 In.-11, Connector Type Threaded Hole, Density Rating High, Flap Disc Type Type 29, Overall Diameter 4 1/2 in, Series HP Aluminum, Backing Material Fiberglass, Grit 60, Maximum Operating Speed 13,300 RPM