With four (4) cells in each Battery Pack, the Power Plus e4 is Hotronicês most powerful, longest lasting FootWarmer!HOTRONICêS FOOTWARMING SYSTEM Easily installs in all types of footwear.Transfers simply from one pair of footwear to another. Use while skiing, snowboarding, bicycling, horseback riding, fishing, and during other general cold-temperature activities.HOTRONICêS BATTERY PACK e4 Powered by high capacity, cold temperature operation, NiMH cells. Four (4) temperature-duration settings.Settings adjusted by easy to use, push-button controls.Easy to read Battery Pack LEDs indicate setting selected and power on / off.Battery Packs easily attach to secure area of footwear.Battery Packs e4 contain four (4) cells for extended duration. NiMH cells do NOT have –memory effect” and do NOT require fully discharging before fully recharging.Temperature & Duration ChartSettingApproximate Average TemperatureDuration RangeçFçC184 – 9529 – 3516.5 – 19.5 h2107 – 11842 – 487 – 9.25 h3122 – 13250 – 565 – 6.5 h4158 – 16870 – 762.5 – 4 hBased on battery pack in ambient temperatures of -22ç to -15ç C (-9ç to +4ç F). Based on heating element in ambient temperatures of 20ç to 26ç C (68ç to 79ç F).HOTRONICêS RECHARGER POWER PLUS e / m SERIES Advanced global charging technology with overcharge protection and input range of 100V-240V. Includes North American and European plug adapters. Recharger LEDs indicate recharging mode and battery charge status. Compatible with both e Series and m Series Battery Packs.HOTRONICêS HEATING ELEMENTS Large oval Heating Elements provide effective anatomical coverage of toes. Heating Elements easily install in Hotronicês Heat Ready Insoles (Semi Custom Heat Ready Insoles or One Size Fits All Heat Ready Insoles) or on insoles of your own choice. Self-Adhesive Fabric Covers and Strips included for installation on insoles of your own choice. CONTENTS IN BOX 2 Battery Packs e4 with Integrated Heat Regulator.1 Pair of Heating Elements with Self-Adhesive Fabric Covers and Strips. 1 Recharger (global input 100-240VAC, 50/60Hz) with North American and European Plug Adapters. Operating Instructions & Limited Warranty Card.