Never used one or saw the need....until we went FT traveling all over the USA.
Ours has shut down due to LOW Voltage (which WILL destroy motors), identified 'open ground, open neutrals and even a reverse polarity issue (which can be dangerous IF ground circuit gets lost also)
Just like a good quality water pressure regulator.......cheap for those what if's that happen. And should there be an 'event' it's TOO LATE. Damage is done.
Progressive Industries,....hands down
Life time warranty..they stand behind it also with great customer service and a tech support that will actually troubleshoot with you on the phone.
Purchase to 'surge & protection' unit...portable or hardwired. About $400 but worth it......RV electronics are expensive to replace!
TRC--Surge Guard has them also BUT only 1 yr. limited warranty
Choice is easy!
On Edit:
They do list 'surge protection recommended' in their Park Rules.
That is a first......never seen a park post that. Have had staff mention it at check in (during high use/high temp periods) but not part of the written rules etc.
Have seen 'Caution: High water pressure----regulators recommended'
Seems they are aware that AC Voltage issues can/do happen...even when NEW.
Lawyer CYA...."we told them!"