NortonĀ® Metal 66252843609 Grinding Wheel, Type 27 Depressed Center, Outside Diameter: 4-1/2 Inch, Thickness: 1/8 Inch, Arbor Hole / Thread Size: 5/8-11 Thread, Grade: T (Hard), Grit: 24 (Coarse), Abrasive Type: Aluminum Oxide, Max Speed: 13580 Rpm, Mounting: Threaded, Product / Materials Abraded: Metal/Stainless Steel