Adapter Model: This trailer plug adapter converts your car's 13-pin plug to a 7-pin female plug. Plug this small adapter into the 13 pin socket then plug your standard 7 pin socket. Suitable for European standard trailer: This 13 to 7 pin socket is suitable for European standard trailer. Establishes a secure connection between your main vehicle and the additional trailer; transfers electronic signal lights from vehicle to trailer. Weather Resistant Sockets: Plastic housing prevents rust and improves appearance. Waterproof for all roads and weather conditions. The weather-resistant spring-loaded locking flap protects connections when not in use and locks the 7-pin plug when in use. Slim design: same diameter as a plug of normal trailer length and just over half the length. Provides power to your caravan, trailer and truck.