Drill Bit Set, 29 Piece, Black and Gold, 1/16" to 1/2", with 3/8 Reduced Shanks, in Metal Index IRWIN offers a complete line of Metal Twist Drill Bits, including Black Oxide, Turbo Point, Titanium Nitride, and Cobalt Drill Bits.. IRWIN Black & Gold drill bits feature a 135 split point tip for accurate drilling without a center punch. Oxide treatment resists corrosion, helps prevent bit from rusting. Turbomax tip starts up to 10x faster. Flatted shanks above 11/64" eliminates slippage in drill chuck. Reduced shank above 3/8" allows the use of larger drill bits in a 3/8" chuck. Rubber overmolded case protects kit if dropped. Tap & Drill selection chart for convenient reference.. Automatic indexing for easy bit access and identification.