If you're adding remote air system couplers in your rig or trailer here's the fittings you've been looking for. On one end you just slip 3/8 OD air line into and it locks. The other end has 1/4" FPT to accept a coupler. Mount the fitting through a hole in a bracket, a trailer wall, or any sheet metal to hold it all in place. If you need 3/8 OD air line ask us. We sell it in any length. These are sold individually and not in pairs as pictured.