Aluminum oxide general purpose wheel for grinding steel and other ferrous metals in normal working conditions. High stock removal. Good wheel life. 4" x 1/4" x 5/8", Type 27, A24N (US616745000) Maximum speed 15300 RPM 4 1/2" x 1/4" x 7/8", Type 27, A24N (US616726000) Maximum speed 13300 RPM 5" x 1/4" x 5/8"-11, A24N (655730000) Maximum speed 12300 RPM Silicon carbide general purpose wheel for stone, concrete, cast iron, ductile iron, masonry materials, non-ferrous metals, brass, bronze, etc. High stock removal. Good wheel life. 4" x 1/4" x 5/8", Type 27, C24N Maximum speed 15,300 RPM 4 1/2" x 1/4" x 7/8", Type 27, C24N (US616729000) Maximum speed 13300 RPM 5" x 1/4" x 7/8", Type 27, C24N Maximum speed 12300 RPM 6" x 1/4" x 7/8", Type 27, C24N Maximum speed 10200 RPM 7" x 1/4" x 5/8"-11, C24N (655660000) Maximum speed 8500 RPM 9" X 1/4" X 5/8"-11, C24N (655672000) Maximum speed 6600 RPM 9" x 1/4" x 7/8", Type 27, C24N Maximum speed 6600 RPM