Tiger Zirc, 58070, Depressed Center Grinding Wheel, Performance Line, 4-1/2 in Wheel Diameter, 1/4 in Wheel, Quick-Change Connector, 24 Grit, Coarse Grade, Zirconia Alumina Abrasive, Wheel Type Number: Type 27, 13300 rpm Maximum, Resin Bond, Applicable Materials: Carbon Steel, Structural Steel, Cast Iron, Steel and Stainless Steel, 5/8-11 Center Hole Thread, Wheel Hardness: T, Reinforced: Yes, Specifications Met: ANSI B7.1-2010