The John Guest 5/16 in. x 1/4 in. Push-to-Connect Reducing Elbow (10-Pack) fittings are manufactured from white polypropylene and equipped with EPDM O-rings utilizing John Guest’s push-fit technology to make easy, reliable, leak-free connections. They have been developed to satisfy the compatibility needs for a wide range of applications and can be used on plastic or soft copper tubing. To make a connection, the tube is simply pushed in by hand; the unique John Guest collet locking system holds the tubing firmly in place. Disconnection is just as easy and requires no special tools.