The North Face Bighorn
Source: bought it new
Price Paid: $99
Definitely NOT a 20-degree bag.
Though this bag is no longer available for purchase new, I thought I'd add my two cents anyway because I want to echo the sentiments of the other reviewer. I originally purchased two of these bags for a summer backpacking trip to the Big Horn (coincidence) mountains. The bag was great there. It was big and roomy, temperatures got down into the 40's at night, and I slept wonderfully.
A few months later, I used it in the Wichita Wildlife Refuge in my old 3-season Walrus Tristar tent with the rainfly on and zipped closed, and slept on a big, thick Therm-A-Rest Camprest sleeping pad. Temperatures hit in the 28 to 32 degree range outside, which meant it was probably 35 to 40 degrees inside the tent. I shivered all night, and I'm warm natured.
There is no way this comes close to being a 20 degree bag. If you find it used for cheap, and want a big sleeping bag that you will never use below 45 degrees or so, it would be a decent purchase.
Design: modified mummy
Temperature Rating: 20F
Weight: heavier than advertised
Price Paid: $90
Believing the temperature ratings on a North Face bag can be hazardous to your health. This bag is rated 20F. It will probably be okay at 40F, but you could get in serious trouble at 20F.
North Face is very tight lipped about exactly what the H.O.T. insulation used in this bag is. But you shouldn't be too concerned because there is almost no insulation in the bag.
The bottom line on sleeping bag warmth is loft--how thick the insulation layer over you is. I test any bag's insulation by putting one hand inside the bag, and the other outside. I then try to lightly touch my fingers together to get a sense of how thick the insulation is. On this bag my fingers touch like there is nothing there, so the fact that it works down to 40F is fairly miraculous.
Once upon a time North Face made good gear, but for quite some time now their business model has been based on catering to urban fashion horses. It is possible to initiate the vicious cycle of hypothermia in temperatures as high as 50F. Add water, fatigue, and hunger, and it could be your last night out.
I bought this bag by mail, and kept it only because it is large enough to serve as a shell for another bag. A two bag system is quite versatile.
Price Paid: $99
I bought this bag (size long) in 2008 as it is roomier than most, and I have broad shoulders and a 48-50" chest.
It is a little bulky but a good compression sack takes care of that. I have used it in higher elevations in the early summer on 6' of packed snow as well as early fall hunting trips, both occasions it dropped down to about -5C and I was warm. I also use the Thermarest Prolite 4 so that definitely plays a factor in staying warm.
I store it loosely stuffed in a giant cotton sack to retain its loft.
For the price you really can't go wrong.
Fill: H.O.T.™ SL
Temperature Rating: 20°F/-7°C
Weight: 3 lbs 15 oz
Price Paid: $60+/-
Went to Big Bear, slept in a cabin (nights in cabin ranging in the 40-50s) with this bag and was very pleased.
When bundled up it was like described and according to the small form factor, yet when open allowed sufficient room to move around. This sleeping bag is slightly bigger than normal which was what I was aiming for since I like room to move around.
There was one slight issue with the zipper however which did get stuck at times due to the inner flap (to keep heat in) getting caught on the zipper. Simple enough to correct with just a little attention while zipping.
All in all, this is a great bag which I recommend to all looking for a roomier bag that will keep you warm.