Product Description Bonded Aluminum Oxide Abrasive, Medium Grit, Replacement Wheel for 6-Inch Bench Grinders, Maximum 4200 RPM, 6-Inch Diameter, 3/4-Inch Thick, 1/2-Inch Arbor. Gitachi 6 inch Grinding Wheel features: Replacement Aluminum Oxide Wheel for 6 inch Bench Grinders, Maximum 4200 R.P.M. 60 Grit, 6 inch Diameter x.75 inch Thick x.5 inch Arbor