39/64 Drill Bits High Speed Steel Reduced Shank Drill Bit USA Made 1/2 Shank Domestic Drill Bits by Bisco of Florida. Reduced Shank Drill Bits are .6094 Decimal Equivalent, 3" Flute Length, and 6" OAL Overall Length with a 1/2" shank. High Speed Steel Reduced Shank Drill Bits expand the size range capacity of a portable drill chuck. USA Made Reduced Shank Drill Bits have common flute and overall length for minimal adjustment during tool changes. Drills are precision ground for high degree of concentricity between shank and body diameter. High Speed Steel Reduced Shank Drill Bits are ideal for drilling in low and medium tensile strength materials.