The Gerbing 7V heated sock liners are the best battery-powered socks available. Equipped with powerful Gerbing 2200 mAh batteries and powered by Gerbing's patented microwire heating elements, these socks will provide up to 7 hours of temperatures up to 150° F. The heating elements cover both the top and the bottom of your foot for maximum warmth during all of your winter activities.Features & Benefits:Heats both the top and bottom of your footMicrowire heating elements deliver evenly distributed heatLifetime warranty on the heating elements Moisture-wicking Fabric Special long cut pulls over your calf to fit any boot or shoe Touch-Button Temperature ControlHOW TO USE:Charge Up– Fully charge power bank with provided charger cable.Plug-In – Connect the battery to the plug coming out of the sockTurn On– Press and hold touch-button control. Press the touch button to adjust the temperature.Material Content: 87% Polyester, 13% SpandexEstimated Heating Times:High(Red): 140F – 3 HoursMedium (White): 120F - 5 HoursLow (Blue): 100F – 7 HoursIncludes:(2) Gerbing 7 Sock Liners(2) Gerbing 7V 2,200 mAh Batteries(1) Gerbing 7V Dual Charger