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Battery Details

Don't confuse this with the LR60 as that is also called a "164", or the A32, which is 9 volts.

Equivalents:

4LR52, 4MR52, 4NR52, 1404A, 1404M, 1410M, 164, 164PX, A32, A32PX, E164, HM-4N, PC164A, PX32, PX32A, PX32AB, PX32B, RPX32, RPX-32, TR164, TR164R, V164PX,

Image not to scale.	Common Name.	Dimensions. Length × Diameter.	Chemical Composition.	Nominal Voltage.
	PX32.	44.9 mm × 17.1 mm Contacts: "Pip" Positive Raised or flat area opposite end Negative.	Alkaline replacement for original Mercury.	6 volts. (5.4 volts for the discontinued Mercury types)

An extremely difficult battery to find! There are some available if you look hard enough but you can make a good bet that yours will go flat when you can't find any.

To replace it you could use a stack of 4 LR52 (gives correct size), or use an A544 6V Alkaline battery or equivalent, though I'd stay away from the Silver Oxide 6.2 volt type if replacing a Mercury original. Add a small spring to take up slack. Wrap the A544 and spring in some cardboard to make it roughly the same diameter as the original, the spring, as shown right, will make up for the difference in length.