Application: Excellent for polishing, sanding, grinding and finishing Stainless Steel, Mild Steel, Aluminium and other metals, plastics, copper etc. Material:Aluminium Oxide Diameter: 115 mm/4.5 Bore Size: 22 mm/7/8 Type: 40GRIT max. speed 13300Rpm Quantity: 4.5 flap disc 50pcs x 40 Grit Manual measuring, please allow 1 ~ 3 mm error,thanks