The structure of these socks doesn't feel much different from regular socks, even though they include Therm-Ic heating elements. Therm-Ic products help keep your feet warm almost unnoticeablythe idea is not to generate all the heat with the battery, but to encourage the body to maintain blood circulation by providing controlled heat impulses. - Compatible with separately purchased Therm-Ic batteries - S.E.T. (Smart Elastic Technology): even better fit, as the heating elements do not interfere with the fit - 69% polyamide, 29% merino wool, 2% elastane - Battery holder at the top of the sock - Heating elements are placed in the toe area