IRWIN 73831 Jobber Drill Bit, Spiral Flute, 4-3/8 in L Flute, Reduced Shank, 31/64 in Dia x 1-1/2 in L Shank | M-2 high-speed steel for strength, heat resistance, and wear resistance in general drilling of wood, metal, and plastic. The 3/8 in reduced shank fits all 3/8 in drills. Jobber length.