PFERD Performance Line SG Grinding Wheel, Depressed Center, Type 27, 5 in Diameter, 1/4 in Thickness, 7/8 in Arbor, 24 Grit, Extra Coarse Grit Grade, Silicon Carbide Abrasive, Resin Bond, 12200 rpm Speed, Applicable Materials: Cast Iron, Concrete, Masonry, Stone and Tough/Hard Aluminum