Enjoy winter exercise to the full with the Thermic Insoles Set.Each Thermic Insoles Set includes a pair of heated insoles and 1 pair of C-pack batteries. Fitted with ultra-fine heating elements, the insoles diffuse constant heat for immediate well-being and an optimal foot temperature. The C-pack 1700 batteries provide up to 13 hrs of heat. Some are also fitted with the Bluetooth function, enabling you to remote-manage the heating via smartphone: Thermic Heat Control Ap Includes a pair of heated insoles Includes 1 pair of C-pack batteries Ultra-fine heating elements Diffuses constant heat for optimal foot temperature C-pack 1700 batteries Up to 13 hours of heat Available with Bluetooth function Remote-manage heating via smartphone (Thermic Heat Control App)