I agree, I think that their usefulness is greatly over exaggerated. I ran a marathon a few years back where a space blanket was waiting for each finisher. Some of the other runners carried a trash bag for the whole race (to use as a shell in case of rain,... it did!) Well, needless to say, I was jealous of their fashoned parkas at the finish line (55 F and drizzling), they seemed a lot more comfortable than I was in all of of my "NASA" technology!<br> Personally, I would rather have a 3 mil. thick 45 or 55 gal. contractor's garbage bag any day. I've used them in many non-emergency situations, and they have proven their usefulness time and again. When hiking, a few of those along with duct tape and paracord are the must-have expendables.<br>If you are in a situation that puts you at risk to "exposure", remember that the mechanisms for heat loss are : Convection, conduction, radiation, respiration and perspiration. I.E., Insulate yourself from the cold ground, block the wind and trap air around yourself- a space blanket is not ideal for any of these. A little knowledge and a trash bag are a lot better!<br><br><br>