Shop 30 Amp RV Surge Protector 125V/3750W RV Surge Adapter Plug with LED Indicator 30amp 1050 Joules 22500A Max Spike ETL Listed TT-30P TT-30R Power Guard for RV Camper Trailer, support 2 Years Warranty with high quality. Together with the diagnostic chart provides LED indication guide for the following wiring condition: Power ON/Correct Wiring, NO Power/Open Hot, Open Ground, Reverse polarity, Open Neutral, Hot/Ground Reverse, Hot/Neutral Reversed with Neutral Open.