SharkBite 1 in. PEX-A Plastic Expansion Coupling (5-Pack) UA020A5 is a 5-pack of 1 in. X 1 in. plastic expansion couplings designed for use with PEX-A piping systems. This coupling requires a PEX expansion tool and expansion rings to install - once expanded and fitted, it forms a secure, full-flow connection that actually grows stronger over time. It's approved for water service lines and is suitable for burial applications, including installation in concrete, which makes it a solid choice for water supply or underground plumbing jobs.