Flap Disc Abrasive Type Coated Abrasive Material Zirconia Alumina Grade Coarse Backing Plate Material Fiberglass Connector Size 7/8 in Connector Type Unthreaded 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 36 Maximum Operating Speed 13 300 RPM