Hand warmer

Under Hand Warmer is defined as a portable heat source for the hands. They come to the very different physical and chemical principles:

Heating pads or heating pad: regenerable latent heat storage
Disposable hand warmers, heat generated by the oxidation of iron powder
Pocket Warmer, metal containers, generating electricity from burning coal or gasoline heat
Heat ball, an early form of Taschenöfen
Charcoal warmers

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