United Abrasives SAIT C16 Grit 5" Dia X 2" Silicon Carbide Concrete Cup Stone with 5/8" - 11 arbor is ideally designed for grinding metals, cleaning castings, mold marks and removing flash. Type 11 cup stone with 7250 RPM features metal backing and coarse grit to render higher stability in tough grinding applications. Cup stone is perfect for maximum surface area coverage for foundry and finds its applications in masonry, stone. It is sold as 6 per box.