Sizes: 1/16" - 1/2" by 1/64" in a unique round Bit Cooler drill index combines form and function into one beautifully designed, easy to carry drill set.. Cobalt drill bits are are effective in drilling tough, high tensile strength materials. Display high red hardness, permitting speeds up to 30% greater than with conventional M2 high speed steel. 135° split point tip for fast penetration and accurate drilling. For use in hard materials such as inconel, stainless steel and titanium