Drill America 60 piece 135 degrees split point heavy duty drill bit set comes in a metal case. Manufactured to National Aerospace standard 907. These drill bits display high red hardness, permitting speeds up to 30 percent greater than with conventional M2 High-Speed Steel, and are especially effective in drilling tough, high tensile strength materials like stainless steel, inconel, and titanium. The 135 split point is self-centering and reduces thrust. Cobalt steel tools are similar to high-speed steel, but with more cobalt for improved performance when cutting harder metals such as stainless steel or nickel alloys. Gold oxide is a thinner oxide surface treatment than black oxide typically used to identify cobalt steel tools; performance is similar to uncoated tools. Round shanks allow use with a wide variety of toolholding systems. When run in a counterclockwise direction (right-hand cut) spiral fluted tools evacuate chips up and out of the cut to reduce clogging. Set include #1 to #60 wire gauge sizes.