I ordered the bag for a climbing trip in the Chugach Range, Alaska. We were expecting temps around freezing, at our camp at 5500 feet on the Icicle glacier. The bag performed brilliantly. I used it with an Integral Designs Endurance Bivy. I slept in the bag after hard days climbing in temps. ranging from 40f to 20f with rain and snow. We camped with a Hex 3 Golite shelter (no floor). I was comfortable in this range of temps. and the bag breathed well. Even my sweaty socks did not pose a problem. The bag does shed a bit more down than my other bags, but not excessively so. The feel of the bag is great with the zipper and drawcords easy to use. At 2 pounds total weight with an amazingly small stuff size you hardly know it's in the pack. I have started carrying it on rescue missions. Probably will always use the Bivy sack with it to help with longevity.