This is a #11 x 6-inch High-Speed Steel Aircraft Extension Drill Bit by NEW YORK TWIST DRILL. It is designed for drilling in aluminum, angle iron, cast iron, copper, duct/sheet metal, nickel, and PVC. The bit has a straight shank style and is suitable for use with drills. This drill bit was made in the United States and is ideal for various metal applications. These bits are about 40 years old, never used, coming in a plastic bag, they are from Grumman Aerospace, a total of 10 bits, and are a bit old maybe a tiny bit of rust, These were my Dad's. These are NOS, so the packing is rough. please look at the pictures so there is no buyer remorse,