Hotronic Recharger Power Plus M4/M3. Keep your feet warm and keep your Hotronic charged.FeaturesAdvanced global charging technology with overcharge protection and input range of 100V 240V. Includes North American and European plug adapters. Recharges in 3 hours or less. Recharger LEDs indicate recharging mode and battery charge status. Compatible with both m4 and m3 Battery Packs.