Tiger® Depressed Center Wheel, Performance Line, 6 in Wheel dia, 1/4 in Wheel Thickness, 7/8 in Center Hole, Arbor Connector, 24 Grit, Coarse Grade, Premium Aluminum Oxide Abrasive, Wheel Type Number: Type 27, 10200 rpm Maximum, Resin Bond, Applicable Materials: Carbon Steel, Structural Steel, Cast Iron and General Purpose Metals, Wheel Hardness: R, Yes Reinforced, ANSI B7.1-2010 Specifications Met.Weiler's high quality line of grinding wheels help metal fabrication professionals get the most demanding jobs done right and done fast. Weiler® 57129 Tiger® Performance Line Depressed Center Grinding Wheel, 6 in dia x 1/4 in Thick, 7/8 in Center Hole, 24 Grit