Drill bits are designed for use with Reed drilling machines and Mueller® E5/D5 only; both of which use saddles. These spiral drills are made from strong, high-speed steel, and are heat-treated for longer life. They are black oxide coated for corrosion resistance, and are much easier cutting than other drills as the spiral motion clears chips away from the cut. Recommended for cast iron and cement-lined ductile iron.