Features: Automatically amazes holes when drilling. Dual-flute design for faster, smoother cutting. Quick change 1/4" hex chuck. 4241 high speed steel ensures long life. These step drills are ideal for a variety of materials, from metal, plastic, fiberglass to wood. They also help to enlarge existing holes. 2 flute design tips accelerated penetration without chipping. Tapered step drill bit drill bits only, other accessories demo in the picture are not included. Specifications: Material: High Speed Steel Sizes: 3-12mm: 3.4.5.6.7.8.9.10.11.12mm (Length: 78.5mm) 4-12mm: 4.6.8.10.12mm (Length: 69mm) 4-20mm: 4.6.8.10.12.14.16.18.20mm (Length: 73mm) Shank Diameter: Approx. 6.35mm (Hex Shank) Main Color: Gold Quantity: 3pcs/set Note: No retail package. Please allow 0-1cm error due to manual measurement. Pls make sure you don't mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package Content: 1x3-12mm Step Drill 1x4-12mm Step Drill 1x4-20mm Step Drill Bit