"SURGE PROTECTOR" is a most confusing buzz-word. Electrical "protection" ranges from voltage monitoring and automatic cutoff if high or low limits are reached - to sophisticated VOLTAGE CORRECTION DEVICES that tame high voltage, low voltage or both, moderating voltage to a safer more reasonable span perhaps 110 - 130 volts.
Some "surge protectors" absorb sharp jolts of power that last only slight fractions of one second. Such protectors are found in strips with a plug in wire and four to seven outlets. These power-strips originated the name "Surge Protector". This is confusing since a flash of voltage that happens so fast a person cannot see it using a light bulb at least to me, is quite different than a "surge" like an ocean "surge" or "surge" of a crowd.
This gets more complicated. Trying to decide which type of protection device is most suitable for your likes and needs.
A voltage cutout protector, disconnects your rig from the pedestal if it decides the power can be damaging or incorrectly connected to the park's hookup socket. The downside of such a device is many facilities have grossly incorrect voltages, which can leave a person disconnected overnight, draining batteries if the rig's heater is being used hard.
A voltage correction device attempts to change damaging levels of voltage to that within an acceptable voltage band.
But a voltage correction device may or may not contain additional electronic components that protect against micro-second flashes of high voltage that eventually tire your rig's appliances electronic circuits.
So a buyer needs to -learn- little, about what kind of protection they need for their rig. A voltage safety cutout may or may not do a danged thing for damaging electrical "jolts" which called by their correct name are referred to as "voltage transient spikes".
I would keep this advice in mind as further comments arrive that stresses the "importance of" one type of device over another. I have yet to see an RV'ing product that "Does It All". Pay particular attention to comments that include nothing but glowing endorsements, yet ignore shortcomings of their recommended device.