Mylar Emergency Blanket by "Don't Die in the Woods".
5x7 feet and reflects 95% of your body heat. Wind & Waterproof and can also be used for shelter, signal aircraft collect water just to name a few. They are compact and reusable and only weigh 2oz. They measure 3in long x 2 in wide single. They are Great to have on hand for that unforseen occurrence that may happen. Keep one in your hunting pack, camping and fishing.