exactly AFLM

the whole idea behind a 0 degree F bag is to be comfortable in the most likely extreme of cold we will encounter. It is doubtful we will venture out in anything colder than the nights we encountered in our recent campouts, 20 to 25 degrees F at the worst, a 0 degree F bag should keep us cozy and comfy in those temps and provide a margin of error and a modicum of safety and comfort in case of any unforseen circumstances.

Besides, a 0 degree mummy bag is what DS asked for for scouting, and if his grades are good this 9 weeks I'd like to reward him with one.