Made of high-speed steel. For use on wood, plastics, aluminum, brass, cast iron, stainless steel, or any machinable material. Fits all Do it Best hole saws. Shank Size: 1/4 In. Length: 3-3/32 In. Material: High Speed Steel For Use With: Do it Best Hole Saws Diameter: Flute Length: Shank Diameter: This product can expose you to Cobalt Metal Powder, which is known to the State of California to cause cancer. -