RV/Marine Generator Adapter 50A 4-Prong Plug to 30A RV/Marine Inlet The pins and terminals are nickel-plated to prevent rusting. The NEMA L5-30R is a 30 Amp, 125 Volt, 3-prong locking female connector. The yellow adapter is a NEMA 14-50P to a NEMA L5-30R RV Marine Style..