4-1/2" X 1/4" X 7/8" Metal Grinding Wheel Zirconia alumina grain. High performance grinding wheel for the most demanding applications, highest stock removal rates and ultimate wheel life. Designed for ferrous metals, stainless steel and cast materials. Sizes include 4-1/2" x 1/4" (type 27, threaded and non-threaded), 7" x 1/4" x 7/8" (type 27, threaded) and 9" x 5/8-11" (type 28, threaded)