extremely lightweight and compact bag that should be great as a 3 season bag for me. kelty does not disappoint once again.I bought this for my son for a 60 mile, 12 day backpacking trip this summer. So far he has used it on several short weekend trips and is very happy with it. His only complaint is that the long is still a little short for his 6'0" frame. He complained his toes press into the bottom of the bag so hard that they compress the down and get cold at night.I've used this bag heavily the past few weeks in August for backpacking in the Sierra Nevada. It keeps me plenty warm while also wearing a light base layer. Well made Kelty product. Fantastic valueGreat lightweight bagSure, it’s light. Easy to store draped in a closet. But the zipper came misaligned and there’s no way to fix it. Not warm at 42f, the broken zipper didn’t help with thatI struggled between 2 and 3 stars for this sleeping bag. I loved it at first! It is super lightweight and I’m 5’ 3” so it fit my frame just fine with extra room to spare. The main problem with this sleeping bag is the REASON I BOUGHT IT. I have been camping this summer in 44 degree weather (higher temps too) and when I use this sleeping bag I am freezing all night long. I woke up one morning with icicles for toes. I had to wear pajama pants, sweatshirt, and add an extra blanket yet I was still absolutely cold. Yes i can tell it does retain some heat and in maybe 55 degree weather (50 degree might be pushing it) it could keep you warm throughout the night. I started getting concerned when my friend was saying how warm his sleeping bag was getting and how cozy he was in his 0-degree bag (not sure the brand). I felt a little heat, slow to warm up inside the bag, and I definitely wasn’t toasty warm (mind you it was approximately 55-60 degrees outside). I ordered mine from backcountry because it was cheaper there and I am deeply disappointed. I bought it because I want to go backpacking next summer and I was testing it out. I would recommend getting a 20-0 degree bag from them for the same effect as 40 (haven’t tried this yet myself). I didn’t want the 20-0Degree bag myself because it’s more bulky but I guess I’m going to have to return my bag and keep looking :(. Not worth the money because it unfortunately didn’t work. I have it 3 starts because it was great quality and would work for someone camping in a lot warmer weather.