Hi zexpress,
The information they provided you seems to have filled in at least some of the missing gaps including the thickness of the middle two layers.
The 2.8 lb density they gave you certainly wouldn’t be the density of the base layer.
So far the specs look like this with only a few blanks left to confirm or fill in (ADDED: they just provided me with the missing information on their chat) …
1.5" 3.5 lb gel memory foam: A little on the low density side but also a thinner layer so it should be OK for most weight ranges.
1" 3 lb high performance polyfoam: This is a good quality material
1.5" 3 lb high performance polyfoam: Same comments as above
7" 1.8 lb polyfoam
For most people that aren’t in higher weight ranges these would be suitable specs and there wouldn’t be any weak links in the mattress but I would be a little cautious with higher weight ranges (mid 200’s or higher)…
Their price is also a little higher than some of the other “simplified choice” or “one mattress fits all” choices in post #3 here.
I would also be very cautious about purchasing a mattress from an unknown and very new internet source without more information about who is behind it and the only information they provide is “my husband and I”.
Phoenix