FIR Heating Vest, Made of Imported 100% Polyester Fleece, Uses Carbon Fiber Technology FIR heating vest Using carbon fiber technology powered by compact and unobtrusive rechargeable batteries, which releases the far infrared (FIR) radiant heat to promote the blood circulate Eliminate the inflammation It also has the health-care function for lumbar nerves and the shoulder nerves This heated vest jacket generates consecutive hours of warmth and is specialized for low power consumption, it works efficiently for long time indoors and outdoors usage Can easily fit underneath a coat, providing adjustable warmth for a variety of comfort levels It uses safe, low-power infrared rays to transmit heat throughout the carbon fiber heating elements sewn into the vest/jacket High performance handy lithium ion battery (lithium ion) set plus temperature control Batteries recharge (charger included) and can be removed to machine wash the vest/jacket (waterproof membrane) Made of imported 100% polyester fleece Specify unisex sizes with design pocket to fit battery and connectors to provide you the freedom of movement no matter in indoor or outdoor activities