Cobalt Alloy Steel Drill Advanced Helical Flute Set 6429DSA. Designed to drill through hardened steel and tough alloys more effectively than standard cobalt alloy steel bits. Made from M35 tool steel. Heat-treated in a salt-bath furnace for strength and durability. Precision ground to exacting tolerances. Advanced helical flute design for improved chip removal and drilling accuracy, as well as improved drill time and longer bit life.