User Review: Marmot Hydrogen
Fill: 850 + fill down
Temperature Rating: 30 degrees F
Weight: Store listed at 21 oz.
Price Paid: $209
This is an excellent 3+ season bag that is conservative in its listed temperature rating.
It comes with a heavy nylon stuff sack that is 6"x12". The stuff sack bottom is round. The bag easily stuffed into this sack, and compresses into a approximately a 6"x6"x6" cube. The 850+ fill power down lofts up quickly on its own, and it lofts up even faster if you climb in the bag. The bag's fabric, Pertex, feels good on one's skin and it is slippery smooth. This allows you to roll around and not take the bag with you. I have not weighed the bag. The manufacturer's listed weight is 21 oz.
The bag has a half-zipper. When fully zipped, it locks into place as the manufacturer claims. I have no problems getting into or out of the bag, despite there being only a half-zip. The zipper tape is stiff and keeps the wispy shell fabric from being caught in the zipper. Apparently, the 2008 version has a full zip.
I have used the bag twice in temps below the listed bag rating of 30 degrees F. Both those nights (10 and 11 degrees F) I was wearing a base layer top and bottom, liner socks, thick wool socks, 100 weight micro fleece pants, a 200 weight fleece vest and a thin hat. I was using a Therm-a-rest Prolite 3 (1" thick) underneath me. Both nights I was in a tent.
I have also used the bag on multiple nights in the mid 30's and lower 40's. Each time I slept in just a base layer and a thin fleece hat. I had a a Therm-a-rest Prolite 3 (1" thick) underneath me. I was toasty warm. I would recommend this bag to a friend.