I will update this review as I get opportunity to test out in colder weather. I'm waiting for a few 20 degree days to test out. I bought this for my ENO hammock system to keep me warm in colder weather. The bag requires a sleeping pad for the insulation to be effective. I chose this one: http://www.amazon.com/gp/product/B005I6QZE6/ref=oh_details_o04_s00_i00Having said that the bag is larger. It's about the size of a large watermelon It takes up about half the space in my 65L Coleman pack. It's light enough though. With the hammock packed, sleeping pad and bag, along with assorted gear but no food it came out to about 23 pounds. I guess you could squeeze in enough food into the remaining space for 2-3 days along with all your other supplies ( batteries, knives, toothbrush, etc...).Those were the concerns I had. Nothing to say other than this will certainly keep you warm, hot almost in everything higher than 40 degrees. I had to give up testing it and sleep on top of the bag it was so hot and this was in about 50 degrees.Ill keep testing to give better metrics on temperatures but overall its a great bag, only weighs about a 1lb even with the compression sack. I'd say pass only if you could find a bag that rolls smaller in the same price range. This was great for the price.