1 1/4" ( 1.25" ) UNC thread to 5/8" inch Core drill drills bit Adaptor Adapter
It can help to change the thread from 1 1/4" UNC to 5/8"-11w. When you install this adapter on the 1 1/4" UNC thread drilling machine, you can use 5/8"-11w thread tool. Female threaded : 1 1/4" UNC.