RE: Jon-E-Handwarmer
It is metal about the size of a large pack of cigarettes. You fill it with fuel which is alike like lighter fluid. After lighting it and letting it set, you put it in a felt bag and it gets very warm. Cabela' s / Bass Pro sell them. They do give off a fuel smell but you usually keep them in a pocket or hand warming muff. They come in two sizes with the larger size when full, will last up to 36 hrs.