Tiger Depressed Center Wheel, Combination Long Life Performance Line, 9 in Wheel Dia, 1/8 in Wheel Thickness, Quick-Change Connector, 30 Grit, Medium Grade, Premium Aluminum Oxide Abrasive, Wheel Type Number: Type 27, 6600 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, ANSI B7.1-2010 Specifications Met.Weiler’s Combination Wheels offer flexibility and efficiency when switching between cutting and grinding applications. A third layer of fiberglass reinforcement provides the strength to hold up when grinding, while the type of fiberglass used maintains a fast cut.