Steel Dragon Tools Core Drill Bit Hex Adapter to 13/16" Male for use with SDT DCBK Series Core Bits Core Drill Bit Hex Adapter.425" to 13/16" Male Adapter For use with SDT DCBK Dry Diamond Masonry Core Drill Bits Fits SDT-DCBK-1.5, SDT-DCBK-2.5, SDT-DCBK-3.0, SDT-DCBK-4.0 & SDT-DCBK-4.5