EVERGD Trailer Truck Caravan Electric Plug Adapter 13 Pin to 7 Pin Plug N & S Euro Socket Towbar Towing Electric Conversion Adapter Lead-Twin 7 pin, Copper, Twist and Lock, 12V, 35cm :
4X Towing Adapter 13 Plug Pin To 7 Pin 12N+12S Socket Towbar Electric Conversion Adapter Lead For Trailer Truck Caravan - AliExpress
How to wire up a UK trailer lighting plug #1947 - YouTube
Trailer Light Converter USA 7 to EUR 13 Pin Towing Electric Connector Parts Blade Socket 7-Way Stop/Brake Signal Separating - China Converter USA 7 to EUR 13 Pin, Electric Connector | Made-in-China.com