The PEXA Plastic Expansion Adapter is a 3/4 x 3/4 inch MNPT fitting designed for use with PEX piping. Manufactured by Sharkbite, this adapter is specifically made to allow for expansion and contraction of the PEX piping system. The 5-pack ensures you have extra adapters on hand for any plumbing projects that may require them. Ideal for home improvement and plumbing projects, this product is a reliable and efficient solution for connecting PEX piping in various plumbing systems.