Made just like the originals! These pocket hand warmers use white gas, such as camp fuel or "zippo" fuel. The element must be pre-burned before use, like a lantern mantle. Fuel goes in the cotton filled body, under the element. After lighting element, replace perforated cap. Unit will emit a gentle heat for several hours. Goes out only when fuel is spent. Comes with velvet protector bag. Do not use bag when unit is lit!