Amazon.com: Kohree 4 Way Flat to 7 Way Round Blade Trailer Adapter Plug End 4 pin to 7 pin Electrical Connector with Mounting Bracket for RV, Truck, Car : Automotive
7 Way RV Blade and 4 Way Flat Wire Harness – Nilight
Curt Trailer Connector Adapter - 4-Way to 7-Way RV and 4-Way Flat CURT Trailer Wiring C57672
Trailer Wiring Adapter: 7 Way Euro Round To Flat 4 Conversion Plug