High speed steel material: Made of good quality 4241 high speed steel, has a long service life. It has high hardness and is not easy to rust and will not break. Fast Burr-Free Chamfering: Countersink Drill Bit Set comes with fast, smooth and clean chamfering without burrs. Excellent Performance: The chamfer drill has stable structure, excellent performance and long service life. The 4-piece deburring tool set can remove burrs, metal processing and non-metallic cutting. Parts less than 25 degree hardness: suitable for parts less than 25 degree hardness , such as carbon steel, thin iron plates, insulation plates and PVC plates. 4 Specifications: A total of 4 pieces in the package, come with different specifications, which will meet your different usage needs. Item Type: Countersink Deburring Drill Material: high speed steel 4241 Objective: Suitable for parts with a hardness of 25 degrees or less, such as carbon steel, thin iron plates, insulating plates and PVC plates SpecificationBlade diameter (approx) Applicable hole diameter ( approx) Shank diameter (approx) Total length (approx) 2-5mm10mm / 0.4in2 ~ 5mm / 0.1 ~ 0.2in6mm / 0.2in45mm / 1.8in5-10mm 14mm / 0.6in5 ~ 10mm / 0 , 2 ~ 0.4inch 8mm / 0.3inch 50mm / 2inch 10-15mm 21mm / 0.8inch 10 ~ 15mm / 0.4 ~ 0.6inch 10mm / 0.4inch 65mm / 2.6inch 15-20mm 28mm / 1.1inch 15 ~ 20mm / 0.6 ~ 0.8inch 12mm / 0.5inch 85mm / 3.3inch List of package: 4 x deburring countersink drill Note: 1. Suitable for materials with hardness less than 25 degrees. 2. Please allow a little size error due to manual measurement. Thank you for your understanding.