This hex countersunk plug is a 304 stainless steel pipe fitting with NPT male threads for closing the end of a pipe. This countersunk plug has a recessed hex head for increased leverage with a wrench during installation and disassembly. It inserts into female pipes or fittings and connects with Metric threads, which create a tighter seal than straight threads. The plug is made from 304 stainless steel , which is higher strength and corrosion resistant.