It ain't no Marmot Col, but for the price paid it…
Fill: 800 fill down
Temperature Rating: -20 Farenheight
Price Paid: $180
It ain't no Marmot Col, but for the price paid it is a good value.
I initially saw a Sub Zero listed on eBay. Went shopping on the web and found the bag carried by several shops at prices ranging from $180 to $350 (so shop around).
The insulation is 800 fill down that lofts well. It's got a decent, but crinkly, Pertex shell. The hood and draft collars work well. The zipper is okay, but not great. And the zipper pull is kinda cheesy; purchasers will want to add a lanyard or somesuch.
Comes with a compression sack, but no storage bag.
This is a BIG bag -- almost too big for me. There's lots of airspace that needs to be kept warm... but that also means there is plenty of room in the bag for all the stuff that needs to be kept warm at night... shirt, socks, boot liners, water bottle, snacks, etc. etc.
I've used my Sub Zero at -20 or slightly below and have been comfortably warm.