The ActionHeat Vest Liner is a great option for those who want to stay warm without all those bulky layers. Designed to be worn over another garment and under a jacket, the ActionHeat heated Vest Liner keeps your torso warm. ActionHeat battery heated apparel utilizes innovative technology designed to warm the core body temperature. These revolutionary garments feature built-in heating panels and are made with ActionFlex material that provides lightweight warmth, comfort, and versatility.ActionHeat heated garments use FAR infrared heating and ActionWave heat reflective technology to deliver hours of heat and comfort. ActionHeat allows you to stay warm and enjoy outdoor winter activities longer than ever before. Whether you are ready to ride around town on your motorcycle, hunt, tailgate, or enjoy the chill of the season, the ActionHeat 5 Volt Heated Vest Liner is ready to keep your warm!HOW TO USE: Charge Up- Fully charge power banks with provided charger kit. Plug-In- Connect the power bank to USB plug located in the pocket. Turn On- Press and hold touch-button control for 3 seconds. Press touch-button again to adjust the temperature. Features: Machine washable gentle cycle Powerful Tri-Zone heating system includes 3 built-in heating panels, strategically placed on the chest and upper back to warm your core body temperature Touch-Button Control Technology (3 settings) 4 LED power indicators display power bank battery life Zip front Battery Voltage: 5-Volt Power System: 2 Amp Colors Available: Black Material Content: 100% nylon exterior 100% polyester interior Estimated Heating Times: High (Red): 130F - 2+ Hours Medium (White): 110F - 3+ Hours Low (Blue): 90F - 4.5+ Hours Includes: (1) ActionHeat Vest Liner (1) ActionHeat 5V Power Bank (6000mAh) (1) USB Charging Cord ActionHeat 5V Battery Heated Vest Liner