When I was at the
Bigfoot factory, they were finishing out about a dozen truck-mounted campers in one wing of the building and had some 2500-series 21 foot trailers under construction in another wing. the 2500 does not mean size - it is the series of trailer and connotes thicker wall insulation, etc. Mine is a 21 foot 2500. Its official model is 25B21RB- series 25B, 21 foot, Rear Bedroom