PFERD Performance Line SG Grinding Wheel, Depressed Center, Type 27, 4-1/2 in Diameter, 1/4 in Thickness, 5/8-11 Arbor, 30 Grit, Super Fine Grit Grade, Aluminum Oxide Abrasive, Resin Bond, 13300 rpm Speed, Applicable Materials: Carbon Steel, Ferrous Metal and Stainless Steel, Suitable for: Angle Grinders