Intramco
Intramco makes electrical parts for towing. Autotools stocks Intramco 7 and 13-pin trailer plugs, sockets, adapters and wiring kits.
There are trailer plugs in plastic and metal, sealed sockets and a spare rubber seal, a tow ball cover and wiring kits for 7 and 13-pin connections. Adapters go 13 to 7 and 7 to 13 pin, in a compact mini version or with a 90 cm lead.
Before buying, count the pins on the car's socket and on the trailer plug. If they differ, an adapter connects the two.