What Ross said Maury and Julie. The single door was the RML8555. The two door is the RMD8555. It's cooling unit is slightly different than the RML, and most owners report it cools a bit better. Ours was one of the first several trailers to get the two door (Jan/Feb 2015) and we're happy with the performance so far.
"You can't buy happiness, but you can buy an RV. And that is pretty close."