[C-]Step Drill Bits feature a triple-flute design for enhanced stability, effectively addressing issues of deviation during the cutting process. Additionally, 'C-profile' smoother cutting and 2X increase in cutting speed. [Coating]Step bits coated with aluminum titanium nitride, rated at 89HRC for exceptional hardness and thermal properties. This coating offers superior resistance to heat, wear, and , with high adhesion and low friction. Laboratory tests show it more than steamed black oxide coating for longer bit life. [15 Step Sizes]Spiral flute design, featuring 15 distinct steps from 4 to 32 mm, offers seamless and effective drilling across thicknesses, eliminating the need for multiple bits. Includes 4 mm, 6 mm, 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, 24 mm, 26 mm, 28 mm, 30 mm, 32 mm. [M35 HSS Step Drill]M35 cobalt high-speed steel achieves high levels of hardness and wear resistance through appropriate heat treatment. Its toughness and bending strength surpass those of standard high-speed steel, making this step drill bit more suitable for cutting harder materials, such as mild steel, medium hardness steel, stainless steel. Colour: Black Material: steel Note: The color and style of the bag are random in different batches and cannot be specified. Package Contents: 3PCS Step Drill Bit for Metal(4-12mm 4-20mm 4-32mm) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.