The CO500-6 set of drills comes in a sturdy case to keep the drills safe and in size sequence so it’s easy to find the size you need. The set consists of 13 500-6 fractional aircraft extension drill bits from 1/16 inch to 1/4 inch in increments of 1/64 inch. The drills conform to NAS907 type J standard and all have a 6 inch overall length with short flutes – recommended for stable drilling where a long reach is required. With a 135 degree split point, the low thrust design with self-centering means you get easier penetration. The drills are manufactured from High Speed cobalt and can be used for drilling many materials including steels, aluminum and stainless steel, and have a bronze oxide finish which will ensure clean and accurate holes by preventing workpiece material from sticking to the cutting surfaces of the tool.