DEWALT DW8400 4-Inch by 1/4-Inch by 5/8-Inch Aluminum Grinding Wheel (25-Pack) This are easy to use This are highly durable This is manufactured in China Aluminum oxide grain combination for long wheel life in aluminum and other soft metals 5/8-inch-11 arbor with A30N specs Ideal for specialty grinding for aluminum and other non-ferrous materials Max RPM 15,200 One Year Warranty, One Year Service, 30 day no risk satisfaction