Amazon.com: Oyviny 4-Way Flat to 7-Way Round Blade and 4 Way Trailer Wiring Harness Adapter Vehicle-Side 4 Pin to Trailer-Side 7 Pin and 4 Pin Dual-Output Connector with Mounting Bracket for Truck
Amazon.com: CARROFIX Universal Fit 4-Way to 7-Way RV Blade and 4-Way Flat Female Trailer Wiring Adapter Connector Kit : Automotive
Amazon.com: Trailer Adapter plug, convert 4 way flat to 7 way RV trailer (97015), Model: , Home & Garden Store : Automotive