Best Bag on a Budget
This bag isn't the lightest or the most compressible 0-degree down bag out there; however, it is a reasonable weight (under four pounds) and a reasonable size for backpacking. It also has an EN "lower limit" (comfort for men) rating of 4 degrees F, very close to zero. (The EN "comfort" rating, i.e. "comfort for women" is 17 degrees F.) You will not find many sleeping bags in this price range that are EN rated that low. The ones that are cost twice as much or weigh more and compress less.
I bought this for my son to use for winter camping with the Scouts. It fills the bottom of his Osprey Ace 48 pack, but he has plenty of room left for tent, clothing, etc. We haven't tested it down near zero yet, but I can say this: When I took the sleeping bag out of the packaging, I hung it up by its hanging loops. When I looked at it the next day, it had "inflated" impressively. More loft equals more warmth. It seems like a very warm bag.
I did try the bag on for size myself. I'm a 5ft 7in woman who wears a women's XL or a men's medium to large in clothing. This bag length was perfect for me and would have been fine if I were two inches taller, but the fit would be tight for anyone near 6ft. In comparison, my Marmot Ouray Women's Long bag is supposed to fit to 5ft 10in, but feels longer than this bag. Also, I didn't have much room in the shoulders and arms (ex-gymnast) but this was probably ideal for cold weather because you don't want a bag to be too roomy (too much dead space to warm up.) I would think a broad-shouldered or stocky man would find this a little too snug.
All in all, I'm pleased with this sleeping bag. I'm planning on buying a second one because I have two sons, but I'll buy a Long because the older boy is growing fast.
Went on a December camping trip to the highest peak in Virginia (Mt. Rogers) with Boy Scouts and camped at 4200ft. It was 26F when we got there and never got any warmer. There was snow and ice on the ground and the gusty winds all day and night made the trees look spectacular. But, back to the Kelty Cosmic Zero...I added a silk liner in my bag, wore skins, wool socks and a snow hat and was toasty warm! I'm usually cold in a sleeping bag, even when it's NOT December, but this was comfy, soft and warm. I had a F&S pillow that fit perfectly under the hood and stayed in place all night. It was soft on the inside and outside, the yellow polka-dot color is kinda wacky, but it's a sleeping bag--so what? It did what it was supposed to do: keep me warm at near freezing temps. It did that and then some. It took a while to get the bag inside the stuffsack, but it packed nice and small for the 1-mile hike to the campsite. I'm so glad I made this purchase so I don't have be cold again!
Kelty Cosmic 0 degree down bag
I first used this bag on my Grand Canyon trip between Christmas and New Year's this year. We went for 4 days, 3 nights with an average temp rating of 19 at night. Overall, I really liked the bag. It was cozy and nice to snuggle in. I was actually hot with the bag, but I was also sleeping with UA thermals on. There was some down leakage, but not much, nothing to be concerned with. The bag resisted water from persperation in the tent. The bag is snug, but it's also a mummy bag. As a woman with large hips, I found it easy to roll from one side to the other. My only suggestion would be to add a compression sack for the bag. The stuff sack it comes in works fine, but if you want more room in your pack, I would get a compression sack. From what I could tell the bag will compress nicely. Overall, for the price of the bag I am very happy with it's performance. I believe it's a great starting bag.
Good Bag - Just a Little Heavy
Bought this bag (regular length) to supplement a 20 degree bag for backpacking/car camping in cold conditions. Good, warm bag - even had to unzip during the night to regulate temperature. First time out it got down to 30 degrees and was nice and toasty. Rained all day on the trail - bag was a little damp but dried out quickly the next morning. Bought a good waterproof compression sack to get the size down in my pack - about 8" x 15" compressed. Bag is a little on the heavy side compared to other down bags, which is OK unless you're watching every ounce in your pack. Good bag at a good price.
Good cold weather bag
Have used at temperatures as low as 20F and been warm every time. The bag can absorb water (condensed breath) at the head but this did not affect the perfomrance. The draft collar works well, but if not properly lined up there can be a draft in the bag, so make sure you adjust the hood properly. The worst problem I have had with the bag so far is that the bottom of the stuff sack ripped along the seam while loading the bag, but was able to patch that with some duck tape before the hike.
Warm and Comfy
I got his bag to replace an old down bag that's been on its way out for a few years. Let's just say I wish I'd done this years ago! This sleeping bag is surprisingly warm and fluffy, yet packs down fairly small. I have a size small compression sack that I use with it while backpacking. I would recommend this bag for cold weather camping only. In my experience, anything over 35 or 40 degrees will leave you sweating and unzipping the bag.
It has only been down to 39-40 F so far with me using this bag but I can tell you that it is very warm at those temperatures. The hood is comfortable and the bag isn't too constricting. I'm a side sleeper and I don't have any trouble rolling over or getting comfy in this bag. I look forward to some colder temps so i can really check it out.
Great Value for Price
Backpacking in the Grand Canyon at the end of December. Spend two nights, one at Cottonwood and one at Bright Angel campgrounds. First night was pretty cold, but I stayed warm and comfortable. I move around a lot and felt the bag was not restrictive. So it is not the lightest or smallest, but hey for the price it worked like a charm. Glad I purchased it!
It was great! I was in Yosemite Valley over xmas and it went well into the 20s every night. I could sleep in it without the need for socks, hat or a extra pullover. I also camped at 9000 ft for a night and the forecast said it went into the low teens. I was still toasty warm and only had to add socks and a hat.
Awesome bag for the price
Lots of rain / snow / wind first night out in tent. Shell of bag got very damp from tent wall condensation; however, the inside stayed warm and toasty. This down bag is very comfortable and durable, especially for the price. I'm an older guy and backpacking for the first time in 30 years. Comfort means a lot and I was pleasantly surprised.