Tiger® Depressed Center Combo Wheel, Combination Long Life Performance Line, 6 in Wheel Diameter, 1/8 in Wheel Thickness, Quick-Change Connector, 30 Grit, Medium 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, 5/8-11 Center Hole Thread Size, Wheel Hardness: S, Yes Reinforced, Specifications Met: ANSI B7.1-2010