PFERD Depressed Center Wheel, Series: Performance Line SG, 5 in Wheel Dia, 1/4 in Wheel Thickness, 24 Grit, Extra Coarse Grade, Silicon Carbide Abrasive, Wheel Type Number: Type 27, 12200 rpm Maximum, Resin Bond, Applicable Materials: Masonry, Concrete, Stone, Cast Iron and Tough/Hard Aluminum, 5/8-11 Center Hole Thread Size, Wheel Hardness: Q, Yes Reinforced, ANSI Specified Specifications Met