Tungsten Carbide Tialn Coating 5D Coolant Twist Drill Bits Carbide for Hardened Steel. Customizable Dimensions: Flute diameter 0.3-40mm, Shank diameter 4-40mm, Length 38-330mm available. Advanced Coating Options: Available with AlTiN, TiAlN, TiAISI, TiSiN, TiN, DLC, Nano, and Diamond coatings. High Precision Tolerance: Precision grade 0.005-0.01mm ensures accurate drilling performance. Superior Hardness Range: Suitable for materials with HRC45 to HRC65 hardness levels. Enhanced Chip Breaking: Special designed drill tip increases centering and chip breaker ability. OEM and ODM Services: Full customization, minor customization, and flexible design options available. High Quality Raw Material: Made from high toughness, grain-sized carbon tungsten with polished surface.