I bought this sleeping bag because I needed the lightest bag I could find with the most warmth to pack in my 25 liter motorcycle backpack. It's tiny when packed, leaving room for lots of other necessities. We've camped in -2 to -4 degree (centigrade) weather so far this year and I can say that this bag did the business every time. While a little more expensive, it's terrific bag for the money if you're after the lightest, warmest bag around.

This bag is SICK!!!!! I toss and turn quite a bit and although this bag doesn't have a whole lot of extra room I never feel restricted. It's super warm, weighs next to nothing and has a great range of comfort.

I have tried a number of ultra-light sleeping bags, and this is one of the best. From my perspective it meets all of the Manufacturers claims. I would recommend it.

This is the second Marmot bag I've owned and wasn't sure if it could get any better...well it did! I previously owned a Never Winter bag and it suited me very well for the past 3 years, I simply had found a buyer for my old bag and wanted to upgrade and decided on the Hydrogen. A stuff sack can't contain this bag, it just wants to stay lofted all the time! I got the long version even though I am only 5'10" and 170 pounds, simply because I squirm a bit, but the bag as a regular surely would have been roomy enough, so stick with what the manufacturer says, if you're under 6ft, go with regular. Like the company's logo states...Marmot: for life...I will never buy a down bag from anyone else. Period.

I hiked a little over 3000 miles this year using this sleeping bag. I spent many nights in this bag when the temp dropped to the teens. I'm not going to say I was toasty every time, but I wasn't hypothermic either. You can't beat this bags weight to warmth ratio. I could stuff it to fit into a climbing helmet, and fluff it back to life day in and day out. When it was warm out I didn't always have enough ball room... so use it as a blanket. I would highly recommend this bag. Just know its limits and your own.

This bag can't get any simpler. Half zipper and no internal neck baffle Compresses down really really small. Wouldn't recommend use for any wet conditions but that goes for all down bags. I am impressed with it's ease of use and it does everything marmot says it will. Im 5'6 and have plenty of room in the regular.