Dagger-Con Concrete screws are designed for light-duty concrete fastening. Holes must be predrilled with the proper size drill bit, which are also included in each 100 count packaged box. All of our industry standard "blue” long life Dagger-Guard coated concrete screws are also offered in bulk packaging without the bit. Whether the application calls for a Phillips Flat or Hex Washer Head, we have stock on all sizes.