Emergency sleeping bags, mylar bivy sacks, every one has seen these tiny survival bags but, do they work? They work ok but not as great as always advertised. They arent that warm and under certain conditions you can sweat inside them. I discovered a minimalist lightweight trick to making these warmer and a little less wet on the inside with a reflective liner called Thermoflect. I also show a few other tips and tricks for them in this video.