Amazon.com: kitletsuit Combo Trailer Light Adapter 7-Pin Blade to 5- or 4- Pin Flat, with LED Trailer Light Wiring Circuit Tester 7-Way Blade and DC 12V Auxiliary Power Outlet, Weatherproof Covers Included :
Four-Way Trailer Light Tester
7 Way RV Blade Trailer Light Wiring Tester Hitch LED 7Pin Plug Connector Adapter | eBay