Drill America D/A29S-CO-SET 29 Piece m42 Cobalt Screw Machine (Stub) Drill Bit. Gold oxide is a thinner oxide surface treatment than black oxide typically used to identify cobalt steel tools; performance is similar to uncoated tools. Round shanks allow use with a wide variety of toolholding systems; Cutting Angle: 135. Cobalt steel tools are similar to high-speed steel, but with more cobalt for improved performance when cutting harder metals such as stainless steel or nickel alloys. When run in a counterclockwise direction (right-hand cut) spiral fluted tools evacuate chips up and out of the cut to reduce clogging. 29 piece drill bit set comes in a metal case. Any product you return must be in the same condition you received it and in the original packaging. Please keep the receipt. We usually respond within 24 hours on weekdays. Thank you for shopping at our store.