Norton® Gemini® Bench and Pedestal Grinding Wheel, Straight, Series: 57A Alundum®, 6 in Wheel Dia, 3/4 in Wheel Thickness, 1 in Center Hole, 36/46 Grit, Coarse Grade, Aluminum Oxide Abrasive, 4140 rpm Maximum, Vitrified Bond, Brown Wheel, Applicable Materials: 300/400 Series Stainless, Hard/Soft Carbon Steel, Tool Steel, Titanium, Superalloy, Aluminum, Brass, Bronze, Copper, Cast Iron, Ductile Iron and Gray Iron, Wheel Type Number: Type 1