NortonĀ® GeminiĀ® 66243522417 Grinding Wheel, Type 1 Straight, Outside Diameter: 3 Inch, Thickness: 1/2 Inch, Arbor Hole / Thread Size: 3/8 Inch A.H., Grade: P (Medium), Grit: 24 (Coarse), Abrasive Type: Aluminum Oxide, Bond Type: Resin BRA, Max Speed: 18080 Rpm, Mounting: Arbor, Product / Materials Abraded: Carbon Steel/Cast Iron