The primary, the ONLY valid criteria for a sleeping bag is to keep you ALIVE at worse, comfortable at best. When The first thing I hear about a bag is compressability smaller than a body bag warning flags go up. A 45 degree rating is easy to fudge. Our unregulated rating system assumes your in a tent, in good health,fed and falling into some mythical parameter of individual metabolism. Such bags will probably be used a few times a year in nice safe campgrounds with coke a cola machines , porta potties and payphones. The manufacturers know most will go a few years of sporadic use and then go flat or fall apart.Then you go out, buy another one in the latest dayglo colour ad nauseum until you've spent double the price of a good unit. Thats the good news. The bad news is you can die in these things and get a nice certificate that lists exposure or hypothermia as cause of demise <img src="/images/graemlins/blush.gif" alt="" />