Versatile and warm, the 5 V Vest is perfect for watching that extra inning or bagging an early morning peak. This stretchy, water-resistant vest consists of a Polyester and Spandex blended fabric and sports a full fleece lined interior providing ultimate next-to-skin softness. The Tri-Zone Heating System strategically places 3 built-in heating panels on the chest and upper back, with the main purpose of warming your core body temperature. Simply charge up the 5 -Volt Power Bank 6000mAh Battery with provided charging kit, use the USB located in the hidden pocket inside one of the hand pockets to plug the battery in and turn the heating elements on by pressing the chest button controller for 3 seconds. Press the button again to adjust to one of the three temperature settings and it's that simple. The lower the heat setting, the longer the battery will last and vice versa. Layer the Action Heat 5 V Vest over your favorite midweight or under a shell for that added touch of ultimate warmth. 94% Polyester and 6% Spandex Soft Shell Fabric, Tri-Zone Heating System: 3 Built-In Panels on Chest and Upper Back, Two Zippered Pockets, Hidden Battery Pocket, 5-Volt Battery w/2-Amp Power System, FAR Infrared Heating and ActionWave Heat Reflective Technology, 4 LED Power Indicators Display Power Banks Battery Life, High (Red): 150F - 2+ Hours Estimated Heating Time, Medium (White): 130F - 3+ Hours Estimated Heating Time, Low (Blue): 110F - 4.5+ Hours Estimated Heating Time,