3/4" TRANSITION UNION (SLIP x BRASS MIP) is designed to compensate for the difference in coefficients of expansion which exist between CPVC and metal pipe in hot water applications. Solvent welds directly to CPVC tube and adapts to standard female pipe threads. Teflon tape is the accepted method of sealing pipe threads on CPVC fittings. Do not use other materials or componds unless approved by the manufacturer.