Depressed Center Grinding Wheel Abrasive Material Aluminum Oxide Connector Size 7/8 in Connector Type Unthreaded Hole Grit 30 Overall Diameter 4 1/2 in Overall Thickness 0.25 in Primary Material Applicationn Aluminum Compatible Tool Type Angle Grinder Series A30N Wheel Type Type 27 Maximum Operating Speed 13 300 RPM Grade Extra Coarse