Thermic’s S-Pack 1400 B Sock Battery with Bluetooth technology and 10 heat settings is the perfect companion for every heated Thermic sock. Thin and compact, this advanced accessory fits seamlessly with a wide range of Thermic socks and offers up to 16 hours of lasting heat. Easily controllable right from your smartphone, the Thermic S-Pack 1400 B Sock Battery sports an excellent balance between convenience, value, and performance.