http://www.dyersonline.com/progressive-industries-30-amp-portable-electrical-management-system.html
I bought the Progressive Industries 30 amp portable model this year. I confess...I've camped since 1988 without having a problem. But, I have gotten into campsites and discovered the 30 amp service wasn't working, or the 15 amp service didn't. If it only protects your rig once, it's paid for itself many times over when you think of the cost to replace a tv, circuit board of a fridge, microwave, etc. Currently, we're on a three week trip, and it's nice to plug it in first and know that the electrical service is working properly.