When you are out in the wilderness and that unexpected situation wreaks havoc with your plans, then you will want to have one of these 110g survival bivy bags in your arsenal. Climb in, hunker down and seal in that warmth. Unlike that old silver emergency blanket, this is a light & reusable bag that provides total body coverage. It reflects and retains over 90% of radiated body heat.
This 'Heatshield Bag' is made by Lifesystems.