Review on Emergency Survival Mylar Thermal Sleeping by Travis Coffman

I used this product during my overnight stay at Joshua Tree but am not sure if it actually did what it was supposed to do. I used my 20 degree sleeping bags in 40 degree weather and was warm. I slipped into a thermal mylar with a sleeping bag as the outer layer, which I was zipped into. I noticed that my socks were quite damp, perhaps due to the slight condensation effect from the heat of the inner layer compared to the cold temperature outside of the tent. Just saying I'm not sure if in 40 degree weather I need thermomylar along with a 20 degree sleeping bag. The thermal mylar made noise when trying to find a comfortable sleeping position. Imagine the sound of wrapping plates and glasses in newspaper or trying to roll a large plastic bag into a ball.