Nylon. 4PCS ELECTRONIC HEATING PADS: 4PCS Heating Pads system will be compatible with any 5V/2A USB power supplies from cellphone Charger, Cellphone Power bank , Car jump starter, Car phone charger, and others. Not include power bank. WARM AND WIDE TEMPERATURE RANGE: Extra heat from electronic heated pads can warm your body at chilly midnight when you are camping outdoor. If you feel too hot, just simply lower the temperature mode or turn it off. EXTRA LARGE SIZE AND LIGHT WEIGHT: 190CMX75CM. And it only weighs 1.3kg, the carrying bag easy to be packed and carried DURABLE SHELL AND SOFT FILLING: Water proof Polyester shell and Soft hollow fiber polyester filling keep your heat inside. MULTIPLE APPLICATION: Heated sleeping bag is good for sleeping at home, office, backyard, car, RV, mountain and beach camping.