RV Generator L14-30P 30A 4-Prong Plug to 50A RV/Marine Adapter Cord – AC Connectors
Amazon.com: MARVINE CABLE Boat Shore Power Cord Adapter 1.5FT 30 Amp to 15/20 Amp NEMA L5-30P to 5-15/20R Female Household Appliance STW 10/3 Heavy Duty Cable with LED Power Indicator : Tools
AMP UP 125V 30 amp M x 2 30A F Y Marine Splitter Shore Power Boat Adapter 21323 | eBay
MARINCO EEL Pigtail Adapter, 50A 125/250V Male to 30A 125V Female | West Marine