Manufactured from premium High Speed cobalt (HSCo) for drilling tool steels and other hard materials, R15CO NAS907 type J jobber drills are available in letter sizes from A to Z and have a heavy duty design, recommended for use in difficult materials and applications. The 135 degree split point is an aid to self-centering and reduces the amount of force needed to drill the hole, whilst the bronze oxide finish prevents workpiece material from sticking to the surfaces of the drill so you get clean, accurate holes.