Depressed Center Grinding Wheel, Abrasive Material Ceramic, Connector Size 5/8 In.-11, Connector Type Threaded Hole, Grit 36, Overall Diameter 4 1/2 in, Overall Thickness 0.25 in, Primary Material Applicationn Steel, Tool Steel, Compatible Tool Type Angle Grinder, Series Green Corps, Wheel Type Type 27, Maximum Operating Speed 13,300 RPM, Grade Extra Coarse This product contains a chemical that is regulated under California Proposition 65. Warning: This product contains a chemical known to the State of California to cause cancer. -