I saw this product in a Special Operation Magazine. They claim that itis equal to a 3-season bag. Since it is waterproof and windproof, condensation could be a real problem. But, it is definitely lightweight and packs into a small volume.
Size packed: 8.4 x 4.3 x 1.2 in.
Weight: 12.3 oz. (350 g)
They also make a vest with a hood.
http://www.ps-med.com/bps/description_bps01.html
Construction details

Sleeping bag


