1/4"(6.35mm) HEX Shank Countersink Drill Bit Set 1PC/5PCS Woodworking Cutter. HEX Shank Auger Drill Bit for Wood with Quick Change 1/4 8mm-35mm Cutting Dia. Square hole drill can not be used on an electric drill, drill square holes need to fit a square hole drill drilling (mortise and tenon machine) to use.
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