Losing body heat is a major cause of death in emergency. The Leberna Emergency Survival Mylar Thermal Sleeping Bag can increase your chances of survival in all weather, all seasons and all circumstances. It is made of durable insulating Mylar material designed by NASA for space exploration. It retains / reflects back 90% of body heat. It is Reusable, waterproof and windproof. | The Leberna Emergency Survival Mylar Thermal Sleeping Bag is extra large in size, 84 inches in length and 36 inches in width. It has a bright yellow strip on the edge for high visibility. It is intended as an emergency shelter, but it is also great for camping, hiking, and protection from the cold outdoors. | The Leberna Emergency Survival Mylar Thermal Sleeping Bag comes with two packs in one box. Each pack has its own carry bag with draw string. Each pack weight only 2.8 oz (3.0 oz with the carry bag). Each pack is 7 inches by 3 inches. It is very light weight and easy to carry and store in your car, back pack or in your emergency kit. | Upgraded head cover is 21 inches wide. Bivy sack will allow you to cover your head completely. Leberna Emergency Sleeping Bag really keep your whole body warm! 120 Decibel whistle can be used for help during emergency. | For customers who have never purchased a Mylar Thermal Sleeping Bag or Blanket, it is very important to know that the Mylar material is very thin. It is how it is designed by NASA for space exploration. So even though the size of the sleeping bag or blanket is big, they can be folded into a very small size.