Flair-It 3/8" PEX Pipe Cap. Made of durable PVC, this cap is designed to connect two pieces of PEX or polybutylene pipe. Its push-to-connect design ensures quick and easy installation without the need for tools. Field tested for over 30 years, this cap is reliable and long-lasting. Use it to cap off Flair-It fittings, 3/4 inch fittings will fit PEX tubing only. For Pex applications.