Camel Grinding Wheels® Premium Z3 42312 Flap Disc, Type 27 Depressed Center Flat, Outer Diameter: 4-1/2 Inch, Arbor Hole / Thread Size: 5/8-11 Thread, Grade: Medium, Grit: 40, Max Speed: 13300 Rpm, Abrasive Type: Zirconia, Backing: Polyester/Cotton, Bond Type: Resin, Mounting: Threaded, Product / Materials Abraded: Stainless Steel