The Spyder Stinger Mach-Blue armor plated high speed steel (HSS) step bits are high performance metal drilling bits that provide exceptional drill bit quality and durability, drilling performance, and value. The Mach-Blue Armor Plating combined with the advanced M-series alloy tool steel construction and proprietary heat treatment make these bits truly revolutionary - they retain sharper cutting edges for longer, have reduced heat build-up and cutting friction, and increased durability, rigidity, and breakage resistance. These incredibly durable bits are the pro's choice for precision drilling, extended bit life, and value. Ideal for electrical work and other applications in sheet metals, including enlarging existing holes.