Internal dielectric sleeve effectively separates dissimilar metals within the waterway to prevent galvanic and electrolytic corrosion. Nitrile rubber washer is more resilient than PEX and easier to install on rough nipple surfaces. A greater number of thread to thread contact provides a better seal to lined nipples. Specially engineered brass adapter allows direct connection to PEX pipe. Design-certified and manufactured in accordance with ANSI/ASME A112.18.6, ANSI /NSF-61 (Section 9), CSA B125, UL Laboratories MH25826 report, and NES NER-615 report.