The Hole Saw set is made of high quality TCT Carbide (Tungsten Carbide Tipped Cutters), and with High-grade Pilot Drill, extremely sturdy and durable, rust proof. The pilot drill bit is designed to protect the carbide teeth as the pilot drills through the cutting material. It is widely used in hard metal, stainless steel plate, iron, carbon steel, alloy steel, aluminum, cast iron, wood and other general sheet metal. It can used as an attachment with an electric drill and cordless drill machine as well.