Geeking out on temp rating

Layering the quilt over the FF bag while wearing a winter grade down parka and proper head insulation, I could see you easily hitting -5 depending on how hot or cold you sleep. This is determinant on you're pad system being up to snuff for the conditions and you are well hydrated and fed.

Add in some down pants and booties and you could probably go lower. VBL clothing could push that further.

I've used 40° and 20° EE quilts combined down to about -15°F. I think I could have gone lower if my pad was better insulated, and if I had something better suited for keeping my head warm (this was before we came out with the Hoodlum, so I had a kind of makeshift head insulation setup that wasn't that effective).