FlexOvit® HP™ Depressed Center Grinding Wheel, Heavy Duty, 4-1/2 in Wheel dia, 1/4 in Wheel Thickness, 7/8 in Center Hole, Arbor Connector, A24T Grit, Coarse Grade, Aluminum Oxide Abrasive, Wheel Type Number: Type 27, 13300 rpm Maximum, Resin Bond, Applicable Materials: Metal and Stainless Steel, Wheel Hardness: T, Specifications Met: ANSI B7.1. FlexOvit® HP™ A1226 Heavy Duty Depressed Center Grinding Wheel, 4-1/2 in dia x 1/4 in Thick, 7/8 in Center Hole, A24T Grit