These thermal insoles feature two insulating layers designed to keep in the heat while keeping out the cold and moisture. The top layer consists of a polar woollen felt to give you exceptional warmth. The bottom layer is made of a high tech material that reflects the heat back to the feet and blocks out the cold. The clever radiantex layer layer redirects heat back to your feet and keeps moisture out to help keep you warmer and drier longer. the polar white blended woollen felt provides extreme warmth and super moisture wicking proficiency along with excellent cushioning.ideal for use in those cold rubber boots heat rated to 13°1 size fits most trim to fit1 pairfray resistantmoisture wickingrecycled blended feltradiantex thermal layerredirects body heat to feet to keep them warm and drydesigned to fit men's and women's boots and shoes from a women's size 6 to a men's size 12