I've never been a fan of the small uber thin mylar space blankets, they just don't hold up under use. What I have used are the thin blankets marketed by numerous companies (do a search for "space blanket" on Amazon) which come in polyethylene, rip-stop polyester or nylon. One side is the base material in various colors and the other side is aluminized. They are much tougher than mylar but don't pack nearly as small.