Mike Sokol, who is a member here on FRF, has a real good article on surge protectors with built-in voltage protection/monitoring, as well as explaining campground power problems.
Do you need a surge protector for your RV?
I know a lot of the time, our members use the terminology for a surge protector to be all encompassing...which it is not. There are differences between a surge protector and voltage protection.
Mike's great article above may help in the understanding and terminology. Hope it helps.