A complete coupling consists of a plug and a socket (both sold separately) that connect and disconnect quickly. Use them if you need frequent access to a line. All Lincoln plugs are compatible with any of the Lincoln sockets, regardless of the pipe size.

Plugs and sockets with a shut-off valve have a valve that stops the flow when the coupling is separated, so air won’t leak from the line. Those with a clamp-on barbed end insert into a plastic or rubber hose and secure with a clamp or a crimp-on hose ferrule.

Plugs are also known as nipples.

Sleeve-lock sockets connect by sliding back the sleeve on the socket, inserting the plug, and releasing the sleeve. To disconnect, slide the sleeve back and pull out the plug.

Zinc-plated steel is stronger and more durable than other metals. It has fair corrosion resistance, so it should be used primarily in dry environments.

Brass is softer than other metals, so it’s easier to thread together. It has good corrosion resistance.

Note: To ensure a correct fit, make sure that the plug and socket have the same coupling size.