Polarshield emergency blanket is a must to have for outdoorsman, survival and for home or car emergencies. These emergency blankets are made of tough, rip-stop reinforced polyester material, designed from insulation used in space exploration. Waterproof and windproof, will not crack, mildew or shrink. Bound edges for long wear. Retains 90% of the body heat. A great addition to search and rescue gear.