into a bag configuration, it will keep you a LOT warmer. Being able to open it flat lets you wear it around camp, as you hike, etc. Makes it almost worth carrying, if it's a thin, lw, cheap one, that is. The 6-7 lb, inch thick, $300 ones are a bad joke. If you're going to lug around something that heavy and bulky, you'd be WAY ahead to have a quality synthetic bag and a TENT. main value of the thing is to use it to protect your synthetics from fire-ember/sparks.