1/2x3/4fpt adapter. Adapters with Female pipe threads and a Flair-It connection. 3/8" and 1/2" fittings will fit PEX or polybutylene tubing. 3/4" fittings will fit PEX tubing only, to use on polybutylene use adapter model No. 26790. 1/2" PEX x 3/4" FPT