Forget about frozen toes or discomforting pain in the winter mornings or evening. Keep your feet warm and cozy all-day long with the FNDN Base Layer Socks. Thin and lightweight, the base layer socks are designed to be worn under other socks or form-fitting tights for extra warmth during extreme weather conditions. These socks are powered by FNDN’s proprietary Radiant Core Heat™ technology and USB rechargeable BEGO battery system. Small and lightweight, the battery is designed to provide sufficient power with minimal footprint possible.