Depressed Center Grinding Wheel Abrasive Material Ceramic Connector Size 7/8 in Connector Type Unthreaded Hole Grit 20 Overall Diameter 9 in Overall Thickness 0.25 in Primary Material Applicationn Aluminum Steel Compatible Tool Type Angle Grinder Series NorZon Plus SGZ Wheel Type Type 27 Maximum Operating Speed 6 600 RPM Grade Extra Coarse