I believe this is the current US Army Modular Sleep System-
http://www.imsplus.com/index.php?target=products&product_id=29786The bags use Polarguard HV for insulation, but the total weight is about 7 pounds. This is a three part system (four including the stuff sack), not a single bag and it certainly won't fit in a 2 liter container.
Here is some info on the Polargard-
http://www.spgear.org/gear/4562/manatee-lg-rh.htmlThis reads like a TNF press release, but it does give some facts about the Polarguard.