A few months back at a gun show I stumbled across a sleeping bag at a table. First thing I noticed was how huge it was since I am a bigger guy at 6'2 300 lbs. The next thing I noticed was that it did not a zipper but was instead hemmed 1/3 of the way up forming a foot box. The guy said they were made for Smoke Jumpers to allow a quick exit. Kind of made sense to me. I have been rocking it in the hammock and it is awesome. I hate the constriction of a regular bag. I will post a pick later. I have not been able to find any information on these bags or seen another one. BTW it looked brand new and I scored it for $15.- George