Flap Disc Abrasive Type Coated Abrasive Material Aluminum Oxide 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