I have several poncho liners aquired over the years, but I'm with BeeGee, a tropical sleeping bag can be opened up and used as a picnic rug of whatever poncho liners are actually intended for or it can actually be used as a sleeping bag. The British military made the technological jump from blanket to sleeping bag during WWII - seems the rest of the world is yet to catch up
I know the US Army had sleeping bags for Mountain Troops, M1942 and by 1944 was issuing a wool sleeping bag to frontline infantry units in the ETO/MTO. then there was the postwar M1945 bag which was down filled and with a water repellent cover you laced on. That was extensively used during the Korean War.
Our "new" Poncho liner, which is really a sleeping bag, that can be unzipped into the original design, with the same material as the original poncho liner is the cats ass. Mixed with a bivy bag for warm climates, or as a sleeping bag liner that you can wash much easier in cold climates. It also has the hole in the center so that you can throw it over top, when on sentry or in a defensive position. Things that a sleeping bag wont let you do. Hands down one of the best pieces of kit to ever be issued.
I take it you are Canadian yeah?? Nice bit of kit.Tell me do they come with a stuff sack?Or do you have to buy one for it?