Sizes in Set: 1/16 - 1/2 x 64ths; #1 - #60; A - Z Number of Tools: 115 Manufactured to NAS 907 Type J geometry aerospace specifications with self-centering 135-degree split point penetrates hard material without a pilot hole and produces small chips to reduce clogging and gold oxide is a thinner oxide surface treatment than black oxide typically used to identify cobalt steel tools; performance is similar to uncoated tools Heavy duty construction for increased strength and rigidity compared to standard drill bits 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