3pcs HSS Metric Spiral Flute Step Drill Bit Set 4241 Steel Titanium Coated Step Drill Bit Set HSS Metric Spiral Flute Step Drill Bit Set 4241 Steel Titanium Coated Step Drill Bit Set Titanium nitride coating runs cooler and lasts longer Automatically deburrs holes Spiral Flute design is better for faster drilling Step Drill Bits