Seger Heat System Powerpack. Power pack with batteries and a charger for socks Seger SHS-Ski Mid 01 och Seger Shs-Trek Mid 01 Sock. The battery is fastening simpley under the sock's band and connects to the battery poles. the current foes directly from the battery via the knitted contact points to the conducting thread which lead the warmth to the sock's toe. A charger is included so you can charge the battery via USB. The battery has a life of 8 hours and it takes 45 minutes to recharge the battery.