Features: Unique step structure, a single drill bit can drill holes in multiple different sizes. Compared with ordinary twist drill bits, these pagoda drill bits are not easy to break off, effectively saving use cost. This drill bit makes it possible to achieve deburring, chamfering, hole expansion and other functions that twist drill bit cannot complite. High-speed steel construction can extend the life of the cutting edge even under extreme temperatures. Blue coating enhances drill bits' resistance to heat, corrosion and rust. Suitable for workpieces with hardness below 25°, such as iron plate, aluminum plate, PV plate, insulation board, etc. Specification: Material: High speed steel Surface treatment: Blue coating Shank: Triangle shank Drill Bit Size: 3/16-1/2": (6 steps: 3/16", 1/4", 5/16", 3/8", 7/16", 1/2") 1/4-3/4": (9 steps: 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 11/16", 3/4") 1/8-1/2": (13 steps: 1/8", 5/32", 3/16", 7/32", 1/4", 9/32", 5/16", 11/32", 3/8", 13/32", 7/16", 15/32", 1/2") 3/16-7/8": (12 steps: 6/16", 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 11/16", 3/4", 13/16", 7/8"） 1/4-1-3/8": (10 steps: 1/4", 3/8", 1/2", 5/8", 3/4", 7/8", 1", 1-1/8", 1-1/4", 1-3/8") Package list: 5 * Step Drill Bits 1 * Automatic Center Punch 1 * Storage Box