I have this 50 amp Progressive Industries EMS-LCHW50
It also has build-in bypass in case you blow your surge protection and still needs power. You then send in the surge circuit board that is replaced easily by plugging it into the main circuit board.
All other you have to replace or send the whole thing in for repair.
This has really protected my motrohome when I wa soutside the USA and the power was as high as 131 volts per leg. This shuts down until the power gets back in a normal range.
I installed it myself by cutting my main cable and installing inbetween.