Spike, was I just lucky on my surge guard unit, because I didn't know it was to be model specific, just a 30 amp job? Or does one size pretty much fit all? I will be buying another for our new Jayco Eagle 320 RLDS, so your info is appreciated. I did check price with the dealer and it was over 500 installed, but if memory serves, we paid just under 200 and another 70 for installation. Of course, I don't know what brand the dealer had in mind. And while I'm picking your brain, is the surge guard model we've discussed here inferior to or less than what I've seen called ems units? If so, is it a whistle and bells difference or a more substantial difference?