Dewalt Drill Bit Set, 21-Piece, 135 Degree Split Point, 31 Degree, Dwa1181 The DEWALT Black Gold Metal Drill Bits feature a black and gold coating for preventing rust. The tapered web design provides extreme durability to resist breakage. The bits feature a 3-flats shank to reduce spin-out in the chuck. The Black Gold metal drill bits are made of heavy-duty High Speed Steel for drilling into a variety of materials including plastic, wood, and metal. Each bit features a 135 split point tip design to help reduce walking. DEWALT 21-pack black oxide twist drill bit set is ideal for general-purpose drilling materials like metal, hardwood, softwood, PVC and fiberglass Parabolic flute design increases chip ejection in metal and wood drilling applications Black oxide coating helps resist corrosion and increase durability, so your drill bits last longer 135 Split-point tips drill on contact and prevents walking on the hard surface you?re working on 31 Helix reduces over aggressiveness of true parabolic flute, making it ideal for drilling deep holes