This 7-way round pin heavy duty plug is used on the connecting cable between the tow vehicle and the trailer. It fits in many original 1970s Airstream trailer-end receptacles. If you have the round 7-pin receptacle on the front of your trailer (near your propane tanks), it is likely you need this.  You attach this connector to the raw end of a cord like our VTS-819 to create a fully detachable "umbilical cord" between your trailer and truck.  The spring is a strain relief that helps keep the connection between cord and plug from getting worn with vibration. Use quality electrical tape under the spring to seal the connection.

The top pin has a slightly larger diameter than the others. .

If you need a new trailer-side receptacle, you will purchase our VTS-565 socket.  In fact, installing a detachable cord system is a great addition to any travel trailer because it protects the cord from weathering when not in use.  And if it gets damaged on the road, it is easy to replace.