7 Pin Electrics or 12N Electrics
Single Electrics, also known as 12(N), are fitted as standard. They provide power from the towbar to the lights on a trailer or caravan.
If you’re only going to be towing a trailer this is all you need. You can tow a caravan using only single electrics, but the interior functions of the caravan, such as the fridge, wouldn’t have power to them.