This is a great lightweight bag for summer backpacking. It compresses really small and the included compression stuff sack is of great quality itself too. I've used this for a variety of summer camping/backpacking and have had no issues with durability or comfort. This bag is actually true to its temperature rating and I've used it for 38 or 40 degree nights comfortably. Only thing to point out is that it runs rather short. Specs say that the regular is good to 6ft, but if you're 5'10" or up, I'd go long.

The Kelty Light Year 40 is a wonderful down bag that is priced suspiciously low. If you are like me you may be concerned with the quality of this bag due to the low price. Well don't worry this bag is top notch in quality and very warm. I'm guessing they keep the price low by using 650 fill rather than 800.

Despite the light weight the bag is very warm and roomy, I was expecting to be a bit cramped. The bag puffs up with lots of loft and the fitted head portion of the bag is comfy and warm. A zippered foot box is very nice at the beginning of the night and easily shut when the temperature drops. The hip length zipper is much shorter than most bags but I do not see it as a flaw because I do not unzip other bags that far. The zipper does get hung up pretty easy and that's pretty annoying, oddly the female version of the bag has ribbon stitched in along the zipper to prevent this problem. Hey Kelty why isn't this feature on the men's?

The Light Year stuffs down so small that I have to cram things around it in the bottom of my 35L pack so it fills the bottom of the pack and it's feather light (pun intended). In the warmth department I slept comfortably in 25 degree weather with a hat and silk weight long johns, however I was in a tent along with a the rainfly on and that keeps a lot of heat in.

The included compression stuff sack is a nice bonus however the quality of the stuff sack is ho-hum and I would buy a granite gear compression sack and use the Kelty for your clothes. I have not seen a single stray piece of down floating around. The build of the bag is much nicer than my prior Marmot down bag, slightly nicer than my old North Face down bag and as nice as my Mountain Hardware bag.

Buy this bag with complete confidence, you will not be let down (no pun intended). I'm about to order the 20 degree bag for the colder months, Kelty has really raised the bar on reasonably priced down bags.

This is a no frills backpacking mummy for lower elevations. A fleece liner would be recomended if cooler temps are expected. Light weight and dependable. I like the product.