This wrist wrap has a built-in battery operated heater that warms your wrist to around 130° F (54° C). It warms the blood vessels to your fingers keeping them warm too. The wrap is made from durable elastic fabric material with a pouch for the rechargeable battery. It has a fiber heating panel inside. The 3000mAh battery lasts a couple hours. Once fully charged, plug it in to enjoy instant-on toasty warmth.