This liner used in Kamik boots is made up of a three-layer system that works to keep you warm and dry. The first layer of the liner is made up of a moisture-wick polyester felt that transfers perspiration to the outer layers where it can dry quickly. The second layer is identical to the first, and aids in the drying process while trapping warm air to keep your feet cozy. The third and final layer is a thermal foil material that functions as an excellent cold barrier and thermal insulator.