The last time I used anything in mine was a couple of years ago during a 50 backpacking trip with my son's scout troop in the Sawtooth Wilderness. One of our scouts left his sleeping back in the vehicle at the trailhead (intentionally). He thought he would be ok with just a fleece blanket - not a great idea when your hovering 84-90,000 ft elevation mark. I used my dental floss to sew his blanket into a bag and gave him my military grade survival blanket. He wasn't super comfortable (we had snow on 2 nights) but he survived...he also became a big advocate of having the proper gear.