Flap Disc Abrasive Type Coated Abrasive Material Zirconia Alumina Grade Extra Coarse Connector Size 7/8 in Connector Type Unthreaded Hole Flap Disc Type Type 29 Overall Diameter 4 1/2 in Series Z SGP STRONG Backing Material Fiberglass Backing Weight Y Grit 36 Maximum Operating Speed 13 300 RPM