— powered by 1 replaceable AAA cell — ″mini finger″ (″little finger″) battery / accumulator. This option is typical for the most miniature devices, where small dimensions are critical. All replaceable elements are convenient due to, in fact, the possibility of replacement — models of standard sizes AA and AAA are sold everywhere, and the process itself takes a minimum of time. In addition, the user has the choice between disposable batteries and rechargeable batteries; the former are cheaper, but require replacement when discharged, the latter can be recharged, but the battery and charger are quite expensive.
