As an English/creative writing teacher, you can call the trailers anything you want, but I'm getting tired of all the poor punctuation and misspelled words I keep on seeing. Any trailer that "opens" to be a bigger size than when it is towed, is an "expandable". It is getting/expanding to be bigger. An expandable trailer that has canvas as a roof over the bed area, that slides or tips/folds out is a "hybrid" meaning a combination of two or more attributes from multiple sources creating a "new concept". Sorry for the lesson, but with all the discussions of torques,ratios,weight distribution, etc on this site, I found something I DID understand and had to comment. There are times that 1 and 1 do not add up to 2 for me. I'm good at writing, but ain't too good with them there figures.