Bosch 29 Piece Black Oxide Drill Bit Set Split Point Tips Three Flat Shank High Carbon Steel for Wood Plastic Light Gauge Metal BL29 Glue Joint Bit maintain steady forward feeding pressure maintain steady forward feeding pressure without twisting the grinder body in the kerf this bit is engineered with TiCo™ High Density Carbide and protected by Freud’s exclusive Perma SHIELD® non stick coating to reduce heat and resin build up Black oxide coating reduces friction and heat for longer bit life Model BL29 Material High Carbon Steel Finish Black Oxide Point Style Split Point Shank Type Straight (Three Flat on 3 16" and larger) Flute Type Spiral Cutting Angle 120° Surface Compatibility Wood