I have two Nikkormats and they as well as other Nikons of the era used the now-banned Mercury PX625 1.3v batteries to power their meters. I have inadvertently double ordered two conversion kits (already had two but my wife "filed" them) made in Holland that use a machined-out shell of the original battery size, fitted with a diode and into which the standard SR44 (silver oxide) or LR44 (lithium) cells fit. The whole assembly is then inserted in the battery chamber as if it were an original cell. The diode reduces the 1.5v of the newer batteries to a steady 1.3v as per the original specs. I only use the silver oxide type. They're much better than using the Wein zinc oxide type. I can return the surplus ones for a refund, but before I do I thought I'd check to see if there was any interest locally - (Australia). Paid 16 Euros each for them.