As noted. there is no set standard for the ultra light designation.
It basically is a label that the manufacturer puts on a unit to let buyers know that it is lighter than normal for it's size. Just how the weight reduction was accomplished is not usually a point that they will talk about.
So the buyer NEEDS to do his homework. Some ultralights simply eliminate some cabinents, reduce the water tank capacities and eliminate a battery and cut down on propane capacity. This can allow for a lighter frame for even more weight reduction. Some go further by using alternative construction methods such as the luan foam sandwich floors.
The buyer needs to be aware of just what was done to make the unit lighter, and the potential pitfalls of each method.
