👍 Sharp -These square hole drill bits made of bearing steel, hardness 56HRC, lengthened core, sharp cutting edge, continuous blade, quick cuttings, high efficiency. 👍 Our woodworking morstising chisel bits set Only use for the opening square hole and keyhole drill -- Square hole drill can not be used on an electric drill, bench drill, drill square holes need to fit a square hole drill drilling (mortise and tenon machine) to use. 👍 Very cost-effective -- Mortise and tenon square hole drilled...