QUICK COUNTERSINK TAPER 3/8Drill pilot hole and tapered countersink for wood screws. The 2-flute integral design ensures uniform concentric results each and every time. Carbide tipped for long lasting results in hardwood, plywood, plastics, etc. Excellent for Drilling: Natural Woods Man-Made Boards MDF Chipboard Plywood Aluminum/Non-Ferrous Aluminum Composite Material (ACM) Composites Composite Decking Materials. Warning: When drilling aluminum/non-ferrous materials, for optimal results and extended tool life use lubricant or air cooling. Make sure the material is fixed and drill is stable during drilling.