These 7 pin metal trailer sockets use a durable real metal aluminum housing that is unlikely to wear, break or damage in bad road and weather conditions. Pure copper contact pins and waterproof design provide a better and safer connection with your vehicles. These trailer plugs are used for electrical connections between a vehicle and a trailer or caravan with 12V electrical system, transmits the electronic signal from the car/vehicle lights to that of the trailer. Suitable for trailer, caravan, car, tow bar, bike carrier, truck, tractor, van, motorhome.