Dual Spiral Flutes on VACO Step Drill Bits help pull the step bit through material for faster cutting. The Titanium Nitride coating extends the life of the cutting edge. Convenient to use with an impact driver and drill, the 1/4-Inch hex shank provides a firm, positive grip. Available in five step bit sizes with commonly used hole sizes for steel (up to 16 gauge), plastic, aluminum, and wood.