75 Gallon RV Tank Heater - AM-Model 4800-120 VAC

I bought 3 of these for my travel trailer. I followed the directions to the letter. I was on a 500 mile trip, it was raining. I looked in the mirror to see these things dragging on the on the highway by the power cord, dragging and flapping in the wind. Ruined. Didn't even have a chance to see if they actually worked or not. What a waste of almost 500 dollars. It was a sickening sight to see 500 bucks gone in the wind.