High speed heat treated steel: countersink drill bits are made of high speed steel, QUENCHING treatment, so they are HIGH HARDNESS, WEAR-RESISTING and sturdy. Different Sizes: Countersink drill bit set included 5 kinds of sizes:2.8 x 8mm, 3.0 x 8mm, 3.2 x 8mm, 3.5 x 8mm, 4.0 x 8mm, very suitable for using to multi size wood hole drilling. One tool for multi uses, improve your working efficiency. Three Pointed Design: Quickly and accurately drill a smooth hole. Better in centering and no skid.Five-edged chamfer design will fast discharge chips from the hole on both sides automatically.It can effectively prevent the accumulation of debris retention, improve the drilling efficiency. Adjustable Cutting height: 2.5-10.5mm Applies: drilling machinery with chuck or joints,the best adjustable wood countersunk bit set ideal for woodworking. ASIN B0CJQZZQBZ Set Name 5Pcs Adjustable Wood Hole Countersink Drill Bit Set Brand Name dcvbny Shank Type Straight Unit Count 5.0 Count Part Number 6GTYU898UY7TH Point Style Split Point Finish Types Finished Manufacturer belistair Material Type High Speed Steel (HSS) Tool Flute Type Straight Number of Pieces 5 Cutting Angle String 90 Degrees Minimum Bore Diameter 2.8 Millimeters Surface Recommendation Wood