This battery is sometimes referred to as 1/2AA. Don't confuse with the 3 volt 1/2AA or the 1/2AA size rechargeable type that are 1.2 volts.
This is 2 × 1/3N or 4 × LR44 in series with a shrink cover holding them together, and can be replaced by those, and a little ingenuity for the positive "pip", if required.
One point to note is that if the equipment is voltage sensitive it would be best to avoid Alkaline types as the voltage output is not stable over the life span of the battery.
2CR1/3N, 2CR1108, 2CR1108/281, 2CR11108, 4AG13, 4G13, 4G-13, 4H-C, 4LR44, 4LR44EP/1BB, 4LR44P, 4MR44, 4NR44, 4NZ13, 4SG13, 4SR44, 7H34, 23-469, 23-544, 28, 28A, 28L, 28SO, 476A, 537, 544, 544A, 544L, 544S, 1406LC, 1406SOP, 1414A, 4034PX, 6231, A28, A28PX, A544, A54464, CR28L, ETR-S, GP476, GP476A, HM-4C, K28, K28A, K28L, KS28, KX28A, L28PX, L544, L544BP, L1325, L1325F, OX28, P28PXL, PX-28LB, PX28, PX28A, PX28AB, PX28L, PX28LB, PX28LBPK, PX28-S, RFA-16, RFA-16-11, RFA-18, RFA-18-11, RPX28, S1325, S1325S, S28PX, V28PX, V28PXL, V34PX, V4034PX,
not to scale.
Length × Diameter.
|Chemical Composition.||Nominal Voltage.|
|A544.||25.2 mm × 13.0 mm
Silver Oxide (Ag2O).
6.2 volts (Ag2O),
(5.4 volts for original Mercury types).