Featuring eleven different sized wire gauge aircraft extension drills with a 12 inch overall length, the CO500-12 set of 500-12 aircraft extension drill bits conforms to NAS type J standard. The drills have a 135 degree split point, designed to self-center, with low thrust for better penetration. The bronze oxide finish will give clean and accurate holes by preventing workpiece material from sticking to the cutting surfaces of the drill. The extra long 12” overall length, coupled with short flutes is recommended for stable drilling in areas which are difficult to reach, whilst the High Speed cobalt used in manufacture means the drills are suitable for use in aluminum, stainless steel, steels and many other materials.