Hss Step Drill Bit - 4-42 Mm 14 Sizes Round Shank Hole Cutting Tool Quick Working Steel

Made of high-speed steel, durable and long lasting Automatically deburr holes when drilling Nitrogen treated to increase hardness and abrasion resistance 14 sizes, 4-42 mm (4, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42 mm) Suitable for workpieces with a hardness below 25°. Widely used for cutting holes in a variety of materials such as steel, thin, aluminium alloys, insulation boards, PVC boards, etc