This hex nipple is used to convert metric thread to NPT thread, whicn has male metric threads on one end and male National Pipe Taper (NPT) threads on the other end. The adapter has NPT threads for creating a tighter seal than straight threads and a hexagonal shape for increased leverage and use with a wrench during installation and disassembly. It is made from stainless steel 304 for resistance to chloride corrosion and greater corrosion resistance.