Sait® 22610 Grinding Wheel, Type 27 Depressed Center, Outside Diameter: 4-1/2 Inch, Thickness: 1/4 Inch, Arbor Hole / Thread Size: 5/8-11 Thread, Grade: R, Grit: 24 (Coarse), Abrasive Type: Zirconium, Max Speed: 13300 Rpm, Mounting: Threaded, Product / Materials Abraded: Metal