We currently have 2 different power protectors.
One is a Progressive Industries EMS-PT50X model.
Progressive PT50X, click here.I also have a "Power Watchdog" by Hughes Autoformers. It's a 30 amp.
Click here for Hughes Power Watch Dog. "Watchdogs" also come in 50 amp models. Follow the links.
I purchased the 30 amp Power Watch Dog about 2 weeks before we traded our last travel trailer for our current 5er. The TT was 30 amp, and the new 5er was 50 amp. I decided to go ahead and keep the 30 amp for those times we might have to plug the 50 amp trailer into a 30 amp receptacle. (Which we did at first at home).
We used the 30 amp only once at a campground over the last year, we've been fortunate to have had all 50 amp site hook-ups, but I'm hanging onto the 30 amp Watchdog for those ... "Just in Case" events.
On my previous camper, the first protector I got was a 30 amp SurgeGuard. It was plugged in 24x365, non stop, unless on the actual road. It ran for one year and then died. I don't know if it took a power hit, or what, but it died. SurgeGuard would not replace it, and the thing was over $100 when we bought it. I then got a 30 amp portable Progressive for under $100. It worked OK until someone stole it. My third 30 amp was the Hughes Power Watchdog.
I have since purchased a bicycle cable lock I keep attached to the 50 amp Progressive. They aren't cheap by any means. So, I'm protecting my protector!
Meanwhile, I've had good results with my Progressive Industries.
Oh, since I'm sharing, I'll share one other thing I did in my last camper after the first Progressive Industries 30 amp was stolen. I removed the panel where the electric cord was stored so I could access it. I then cut the umbilical cord and put another plug on it. I then attached the opposite end plug back on the original umbilical cord. I now could plug in the power protector, in-line, but not exposed to the outside for theft. If anything ever happened, all I needed to do was plug in the original cord and I was back in business, or plug in another protector if it ever died. After this was set up, I never had issues again. I kept the protector when the trailer was sold, and simply plugged the umbilical cord back in. The new owner can get their own protector: