A special 12" long aircraft twist drill bit made by Triumph Twist Drill Co. These jobber twist bits are made of High Speed Steel to hold their sharp cutting edges longer, & have a black oxide finish. The drill bits have a 135° split point for quick penetration & precision drilling, no walking & no drill bit wandering. These twist bits are for general purpose drilling in a variety of materials. For use in stainless steels, iron & cast materials, low & high carbon steel. May also use in hard & softwoods, aluminum, aluminum alloys, brass, bronze - soft & medium, & plastics.,Triumph Twist Drill has manufactured High-Quality cutting tools for over 50 years. Starting in 1952, founder Harry Beck set out to provide customers with a product that the drill industry had been lacking. Harry, along with his son Jim and Cy Brock, decided to enter the small drill business and create quality, handmade products with the customer in mind. Triumph HSS 12" Long Aircraft Drill Bit