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 150deg F. The heating elements cover both the top and the bottom of your foot for maximum warmth during all of your winter activities. Fit & Design: Heats both the top and bottom of your foot Microwire heating elements deliver evenly distributed heat Lifetime warranty on the heating elements Moisture-wicking Fabric Special long cut pulls over your calf to fit any boot or shoe Touch-Button Temperature Control How To Use: Charge Up- Fully charge power bank with provided charger cable Plug-In - Connect the battery to the plug coming out of the sock Turn On- Press and hold touch-button control. Press the touch button to adjust temperature Estimated Heating Times: High (Red): 140F - 3 Hours Medium (White): 120F - 5 Hour Low (Blue): 100F - 7 Hours Includes: (2) Gerbing 7 Sock Liners (2) Gerbing 7V 2,200 mAh Batteries (1) Gerbing 7V Dual Charger