We had 10,000 pieces of these custom coupling nuts with nylon patch produced for our customer using 18-8 stainless steel material with partial internal thread.  The drilled hole depth was at 19MM max and 16MM of that depth was to be threaded.  Across the flats measures .500″ and overall length at 1.5″.  The undrilled side required a 45 degree chamfer resulting in a .40″ diameter round base.  Nylon patch was applied at 180 degrees after the first 2 threads.