DEWALT DW8404 4-1/2-Inch by 1/4-Inch by 7/8-Inch Aluminum Grinding Wheel (25-Pack) Aluminum oxide grain combination for long wheel life in aluminum and other soft metals 7/8-inch arbor with A30N specs Ideal for specialty grinding for aluminum and other non-ferrous materials Max RPM 13,300 One Year Warranty, One Year Service, 30 day no risk satisfaction