is the short-pile (and often grey) upholstery used in many automobiles. It's soft (like a mouse, if you've ever petted one...) cut-pile stuff, not the looped and rough (kind of steel wool like) style of carpet usually called "berber".
Rats are bigger than mice, so rat fur
is a longer-haired version of mouse fur - you think I'm joking, but I'm serious! I suppose the other possibility is that we call it mouse fur around here, and it's called rat fur elsewhere, because we theoretically don't have rats in Alberta (but have lots of mice), and everyone else has rats.
In the end, the wall covering is not likely the problem, anyway. All of the optional equipment
(maybe stuff like a refrigerator
, water tank and pump, battery
tank, heater, fan...) and sheer reality
(versus marketing idealism) likely account for the difference in advertised and actual weight