Before 1988, the only trailer connector in common use was a 6 pin unit (There were some 5 pin plug/sockets found in Victoria, TAS, SA & NT). Since 1988 you must have a 7 pin (minimum) connector in order to register your boat, camper trailer etc. (You may need a bigger connector in some cases, so consult an auto electrician for this). All trailer plugs and adaptors are made from the highest quality material. A range of the most common 7 pin trailer plugs and sockets, featuring easy to use screw down terminals, corrosion resistant metal contacts and high quality UV stabilised plastics. • In each type, the socket is fitted to the vehicle, and the plug is fitted to the trailer. Often we find that the trailer we've borrowed from a mate does not plug into the socket on your vehicle, and that's where these trailer plug adaptor leads come in handy. About 20cm in length, and 6 versions available to fix up any mismatch of the 7 Pin Flat, 7 Pin Large round and 7 Pin Small round trailer connectors. * Remember, match the plug end of the adaptor to the socket on your car, and the socket end of these adaptors to the plug end on your trailer. Input Type : 7 Pin Round Trailer (Large)Input Connection : PlugOutput Type : 12 Pin Flat TrailerOutput Connection : SocketOutput Quantity : 1pc