Good surge protectors should block electrical current from flowing into your camper if anything is wrong, (wiring, low voltage, high voltage, etc.), and only allow power if everything is ok. It also protects against intermittent campground low voltage issues caused by circuit overloads. Camper units are sensitive due to the 12 volt, 120 volt combination which has sensitive components. It also helps prevent voltage overload from things like lightning strikes. New surge protectors go through a power check sequence before they will allow power to flow to your RV. The portable units work very well, the only down side is that they are subject to theft, not usually a problem most places, but the price of the surge protector may tempt someone, somewhere, sometime. I worried about theft the first time I used one but no longer give it much thought. Nearly all campers are good neighbors and RV owners tend to watch out for each other.