Aluminum oxide general purpose wheel for heavier working conditions for steel and other ferrous metals. Very fast rate of cut. Good wheel life. Flexibility for flush cutting. 4 1/2" x 3/32" x 7/8" Type 27 A30R (US616727000) Diameter x thickness x bore: 4 1/2 " x 3/32 " x 7/8 " Maximum speed: 13300 RPM 5" x 3/32" x 7/8" Type 27 A30R (US616310000) Diameter x thickness x bore: 5 " x 3/32 " x 7/8 " Maximum speed: 12300 RPM 6" x 1/8" x 5/8"-11 A30R (655313000) Diameter x thickness x bore 6 " x 1/8 " x 5/8-11 " Maximum speed 10200 RPM C 30 S - - - - Silicon carbide general purpose wheel for stone, concrete, cast iron, ductile iron, masonry materials, non-ferrous metals, brass, bronze, etc. Fast rate of cut.Good wheel life. 4" x 3/32" x 5/8" Type 27 C30S Maximum speed: 19000 RPM 5" x 3/32" x 7/8" Type 27 C30S Maximum speed: 12300 RPM 9" x 1/8" x 5/8-11" C30S (655303000) Maximum speed: 6600 RPM