Flap Disc, Abrasive Type Coated, Abrasive Material Zirconia Alumina, Grade Medium, 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, Backing Material Fiber Glass, Backing Weight Not Applicable, Coating Coverage Closed, Grit 60, Maximum Operating Speed 13,300 RPM