The UM-3 battery is also called AA, R6 or Mignon cell.

The round battery with a diameter of 14.5 mm and a height of 50.5 mm is used in many pocket travel radios.

The nominal voltage of zinc-carbon batteries or R6 or alkali-manganese batteries or LR6 is 1.5 volts.

Nickel-cadmium accumulators (NiCd, resp. KR6) or nickel-metal hydride accumulators (NiMH, HR6) have a slightly lower nominal voltage of 1.2 volts. Not all sets can be operated with accumulators instead of batteries, as the lower total voltage is not sufficient for reliable operation.

• Information on AA battery and generally on Battery sizes