I got it home and pulled it out of the stuff sack, which IMHO, is on the unnecessarily complex and complex side (the stuff sack), if I use a stuff sack I will shove the underblanket into a spare sil nylon one I have. It is thin so far, but I am letting it uncompress. I intend on using it as a summer UQ and I suspect that is where it will shine. I don't see how this thing is going to handle -5*c temps as advertised. But I sleep cold.
I heard back from DD, they did not know the maker or brand name for the insulation they use in their underblanket.