I bought the featherlite 0 deg. bag because I knew I was going snow camping. Snow being frozen and all I thought I needed a good sleeping bag for the occasion and because it was a hike I needed a lightweight bag. The bag is defiinitely warm but not warm enough to be snow camping. I use a gortex shell around my sleeping bag to stay dry, I slept in medium wieght polypropylene longjohns and was on a thermarest medium weight sleeping pad. We were in a snow cave, however, there's no way I would have slept outside in this bag. I know my sleeping pad was insufficient. I could feel that. But I could feel the cold through the bag and I was inside out of the weather and the outside temperature only got down to 20 degs F. So the ambient temperature never got down to zero and this bag was not warm enough to sleep inside a snow cave, even with a shell over the bag and longjohns. I could feel the chill on any point that seemed to touch the sleeping bag. Elbows, knees, toes. It was a chill. I wasn't going to die but I was chilled all night. Not enough to shiver but definitely enough to be uncomfortable. Disappointing for sure. Construction seems decent. The weight is great. It's just not what it cllaims to be. I wonder how they test that.