The Arc Edge is an extreme bag in the true meaning of the word.

To achieve the ridiculously low weight of 11 oz we had to make some radical decisions. How do you trim total bag weight when already using the lightest materials available? Answer: use less of said materials.

We carefully reworked the pattern to be as snug as practically possible, while still allowing full body coverage. All excess was removed. One underbody straps was eliminated. The foot box was totally redesigned. These changes compromise comfort, particularly with the bag strapped down for cold weather use. No more sprawling out with that feeling of space and freedom. But the payback comes on the trail, when your pack is several pounds lighter.

Instead of making a sewn through Arc Edge, we decided to retain full baffling but reduced the loft to one inch, thus making it a conservatively rated 40 degree bag. If you're a warm sleeper, this has proven to be plenty for a summer bag used mostly at the middle altitudes of for instance the Pacific Crest Trail or the John Muir Trail.