PEX polymer lined nipples comply with dielectric waterway fittings requirements of many municipal plumbing codes. Dielectric waterway nipples help protect the tank from corrosion caused when a dissimilar metal like copper is connected directly to the tank. High quality PEX nipples will not corrode shut, leak or clog with lime scale like plain galvanized nipples commonly do.
For water heater inlet and outlet connections
Reduces heat loss caused by heated water expanding in to supply and outlet plumbing