3pcs 4241 HSS Metric 1/4 Titanium Coated Hex Shank Step Drill Bit Cutting Tool Smoother Drill Bits Basic Bulk Pack Kit Features:Automatically Deburrs holes when drillingDual-blade design for faster and smoother cuttingTitanium nitride coating for coolingQuick Change 1/4" Hex ChuckHigh Speed Steel for Long LifeThese step drill bits are ideal for a variety of materials, from metal, plastic, fiberglass to woodThey also help to enlarge existing holesDual flute tips can speed up penetration without chipping3pcs Titanium HSS Taper Imperial Tire Step Drill Bit Set 1/4" Hex Shank3pcs 1/4'' Large HSS Hex Shank Titanium Cone Coated Step Drill Bit Parts Set With Case3pcs Large HSS Steel Step Tapered Drill Bit Titanium Drill Bit Hole Cutting Set Specification:Material: HSS1/4" Hex Shank Sizes: (Approx.) 3-12mm:3, 4, 5, 6, 7, 8, 9, 10, 11, 12mm/ 0.12, 0.16, 0.20, 0.24, 0.28, 0.31, 0.35, 0.39, 0.43, 0.47 w4-12mm:4, 6, 8, 10, 12mm/ 0.16, 0.24, 0.31, 0.39, 0.47 inch4-20mm:4, 6, 8, 10, 12, 14, 16, 18, 20mm/ 0.16, 0.24, 0.31, 0.39, 0.47, 0.55, 0.63, 0.71, 0.79 w4241 HSS high speed steel (suitable for use in 25 degree hardness workpieces such as carbon steel, plate, insulation board and wood board)Packing List: 3 * step drill bit with bag 1.