The Fox River Wick Dry Therm-A-Wick uses a combination of moisture wicking polyester and insulating Thermolite. Moisture can build up around your foot from perspiration even in cold weather creating increased risk of frost bite but with the moisture wicking polyester perspiration is quickly removed from your foot and transferred outside the shoe keeping your foot dry. Adding a liner to your insulating socks can also increase the overall insulation of your footwear. These liners are combined with Thermolite fabric that has hollow core fibers to trap and retain heat adding yet another shield against front bite or just uncomfortably cold feet. A coating of silver helps eliminate odor by inhibiting bacterial growth within the liner.