Winter Rechargeable Electric 7.4V 2200mah Battery Heated Warm thermal underwear Features : Rechargeable battery electric thermal underwear with Knee, back and waist both heating 7.4v 3000mah rechargeable battery packs,It Starts Heating Within 30 Seconds, duration long heating time. With Far Infrared Fiber heating elements Layer,promote blood circulation and Great for Fear of cold,Raynaud’s , Arthritis , Bad Circulation, Stiff Joints People. Best solution for all kinds of outdoor activities like skiing, fishing, Jogging, hunting, cycling, hiking motorcycling, maintaining climbing walking dogs, running, shoveling snow and so on How to use : Charge Up – Fully charge with provided charger kit. Before using Plug-In – Connect the battery to plug located in the pocket. Turn On – Press and hold the three-second switch button for an initial temperature of 55-65 degrees (red LED), mid-range 45-55 degrees (blue LED), and minimum 35-45 degrees (green LED). Wash and Care Machine wash can be done. When washing, please remove the battery. If it is machine wash, please put the clothes into the laundry bag to wash. To ensure the service life of the clothes, try to avoid strong washing and dry normally.