Drill America Qualtech 26 piece 135 degrees split point heavy duty drill bit set comes in a metal case. Manufactured to National Aerospace standard 907. Made of heat resistant cobalt, they display higher red hardness which permits speeds upto 30 percent greater than High-Speed Steel drills and are especially effective in drilling tough, high tensile strength materials like PH stainless steel, inconel, and titanium. These drills are self-centering and reduces thrust. Sizes smaller than 1/16-inches have the 118 degrees standard point. 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 A to Z letter sizes.