Manufactured from heat-resistant cobalt M42 high-speed steel, these drills maintain their cutting ability at temperatures exceeding 1000 degrees F Left hand helix for screw extractions or other counter-clockwise drilling 3/8"(0.3750") Fractional Drill Bit- 6 per Envelope 135 Degree Split Point Left Hand Spiral Straight Shank Type J Cobalt Bit made in the USA to NAS 907 standards