Hi Jillian,
dn provided all the basic information about “all natural” and “chemical free” I would have provided as well 
You can see my thoughts about Sleep N Aire in post #8 here based on a conversation I had with them and they appeared to be open and transparent about the materials they use in their mattresses.
As dn mentioned … the latex could be 100% natural Dunlop (which means that they don’t use any synthetic latex in the material) but polyfoam (“soy based” or otherwise) is made mostly with petrochemicals that are not natural. The quality/durability of polyfoam is based primarily on its density. They should be able to tell you both the blend of the latex and the density of the polyfoam.
I don’t know the size your friend purchased or the specifics of the materials (again … they could tell you) but the odds are good that they made a good quality/value purchase.
Phoenix