If by "survival blanket" you mean the heavy duty mylar/plastic tarps, you can get them from quite a few catalog companies. Brigade Quartermaster's sells them for around $11.00, I think; green plastic backing the silver mylar, which I prefer to the orange/red of some other blankets. Other than differences in color, I've never noticd any great difference in construction, and they're all about the same size, though I wish *someone* made one just a little bigger. The one in BQM has grommets on each corner, and is pretty stout. Their best use is as a ground cloth, over a bed of browse, or as a reflector as part of a lean-to shelter. They WILL keep you a little warmer, providing you sleep with your clothes on, but they're a little too small for a good sleeping blanket, and the plastic tends to be cold where it touches you. As an outside layer in a wool blanket shelter roll, it serves a purpose.