I test most gear before I will need it. I spent several hours in the weather with this item. 25f, slightly snowing, very slight breeze. I tested while taking shelter under a pine tree next to a log. Here are my thoughts. It is terribly small and constricting. I struggled to get into it with my boots on. If I was much bigger, or injured I do not think I would even be able to use this product, I am 5'6" 165lbs. The bivvy is very small, my feet could barely move. I did not feel warm at all, in fact I felt colder inside this than out. I believe this is due to the bivvy being too small and compressing the loft and insulation in my clothing. I could not see using this with a sleeping bag or other added insulation at all, simply no room inside. I do not think you would be able to put this on another person if you were trying to help them in an emergency situation without serious effort. The material did not feel like it "reflected body heat" at all, in fact I felt cold where the material was touching my arm, back, legs etc. I expected to feel cold on the ground, I was not using a sleeping pad... but to feel the top so cold was surprising. I understand this is not meant as a "sleeping bag" but I spent quite a while in this and was getting colder and colder in it. I actually felt warmer when I got out of it and my clothing was no longer compressed tightly against my body. I highly recommend anyone purchasing this type of item test it out to check if it fits, and see if it actually holds up to the claims on the package. For the near 60 dollars this is sold for there are other options out that may be a better option. Read more