"MUELLER" DIELECTRIC UNION 3/4" x 1/2" 3/4" Male Iron Pipe Thread x 1/2" Copper Solder Joint Prevents Electrolysis Or Galvanizedanic Action When Connecting Dissimilar Materials For Use With Water Up To 210 Degree Fahrenheit Complies With No Lead Standards ANSI B1.20.1 & ANSI B16.18.