This 1.35 volt Mercury cell commonly used in some Bolex cine cameras and some Alpa cameras is now banned because of toxicity and environmental fears.
There is a solution: Batteries of the same voltage and diameter exist (Zinc Air Cell Z675PX or the Wein Cell MRB675 or its' voltage reducing adaptor equivalent). However, these options only have a height of 5.4 mm and some sort of conductive packing is required for the battery to make contact. There are adapters available on eBay and elsewhere that make up the height difference. Some ingenuity on your part could see you using tinfoil, stacks of small metal washers or springs as packing.
NOTE: If using an air activated cell ensure that the battery compartment is not air tight!
You may decide to use a 1.55 volt Silver Oxide equivalent (SR44 etc) with the packing for longevity but note that the light meter may not function correctly.
E-450, PX450, RM450, RM450R,
not to scale.
Diameter × Length.
|Chemical Composition.||Nominal Voltage.|
|PX450.||11.6 mm × 14.5 mm||Mercury.||1.35 volts|