5rv with the highest R factors

We bought a unit from a small manufacturer called Hy Line the brand is Premier Elite. Their main target is oil workers in the northern states. Don't have a lot of marketing materials which can be good because you don't pay for the marketing in the price. We were looking at drv Manhattens and came across this brand. Quality is very good and they avoid the whole real wood and real marble thing (I have to pay for my gas). Anyways this thing is unbelievably efficient. Ours is 500sqft inside and the one ac can hold temps at 74 in 100 degree weather with no problems. Back in April we had the 1500 heater set at 75 were hot opened the front door to 28 degrees and were amazed. Very well built for the price.