The Adventure Medical Kits SOL Heatsheets Emergency Bivvy is an ultralight, emergency bivvy sack that can be the difference between life and death if you find yourself in a low-temperature survival situation. The polyethylene "Heatsheets" material is rip-resistant, windproof, waterproof, much tougher and quieter than mylar survival blankets. Additionally, the Heatsheets material reflects 90% of body heat which can significantly increase your comfort and survivability in frigid temperatures. Another improvement over mylar is the fact that Heatsheets polyethylene is slightly stretchy and can be repaired with duct tape. The blaze orange color on the outside of the bag makes you easier to spot, which is exactly what you want if you are ever caught out in the elements or injured.