Insoles are made of a layer of woven sheep wool on polyester fiber, a layer of 4-lb density foam, and a metabolized membrane which reflects heat. The insoles we sell are the same that come in brand new boots; feel free to replace them as often as needed to keep your feet comfortable, warm and dry. And why not try our insoles in any other boots, such as ski boots, to bring a little bit of Saute-Mouton warmth to them?