Soft and Breathable FabricCycling Feet Warmers are made with 52.5% nylon material, 22.5% Viscose, 10% polyester, 15% Spandex.Breathable,Quick Drying,Heat Insulated,,elastic thickened,using electric modules,and recessed heating element help to focus heat in the bottom of foot and toes to keep your feet from getting cold.