CGW Bench and Pedestal Grinding Wheel, Straight, 6 in Wheel Dia, 3/4 in Wheel Thickness, 1 in Center Hole, 60 Grit, Medium Grade, Aluminum Oxide Abrasive, 4456 rpm Maximum, Vitrified Bond, Blue Wheel, Applicable Materials: HSS Over 55 RC and Above, High Carbon Tool Steels and Woodworking, Wheel Type Number: Type 1, Wheel Hardness: K.