and high quality Automatically Deburrs Holes as you Drill.Two-flute Design Gives You Faster, Smoother Cutting. Titanium Nitride Coating for Cooler Running.High Speed Steel for These Step Drill Bits are for variety of materials from metal, plastic, fiberglass to wood.They also help to enlarge existing holes.Quick-change 1/4 inch Hex Shank The two flute design tips made the penetration faster without chipping color: Gold Materiel: High-Speed Steel Sizes of Drill Bits: 3-20mm Package includes: 3 x 1/4 inch High-Speed Steel Step Drill Bit 3-12mm 3 x 1/4 inch High-Speed Steel Step Drill Bit 4-12mm 3 x 1/4 inch High-Speed Steel Step Drill Bit 4-20mm 3 x OPP Bag 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.