Cobalt aircraft extension drills are manufactured to aerospace standard 907. Aircraft extension drills are ideal for drilling aluminum and mild steel where extra length for reach is required. The 135° split point is self-centering and reduces thrust.

Cobalt is harder than high speed steel and provides better wear resistance. It is commonly used on high tensile alloys. Oxide prevents chip building, galling and welding on the work piece. It is commonly used on low carbons, stainless steel and iron based ferrous metals. Spiral flutes are constructed with a higher helix rate to remove chips more easily. Regular, also known as medium helix bits, are used in general purpose applications. They are used on soft, non-ferrous materials.