Depressed Center Grinding Wheel Abrasive Material Aluminum Oxide Connector Size 7/8 in Connector Type Unthreaded Hole Grit 36 Overall Diameter 4 1/2 in Overall Thickness 0.125 in Primary Material Applicationn Aluminum Brass Bronze Cast Iron Copper Stainless Steel Steel Compatible Tool Type Angle Grinder Series Challenger 3 Wheel Type Type 29 Maximum Operating Speed 13 280 RPM Grade Extra Coarse