WEINCELL (MRB675), Replacement (12-Package master carton) Wein Cells are the only mercury-free, exact-voltage replacements for discontinued 1.35 volt mercury photo batteries. The zinc/air composition of the WeinCell delivers the same precise voltage with steady, constant output identical to that of the mercury batteries (alkaline replacements are generally 1.5 volts, with an unstable output curve this can result in exposure errors of up to 2 stops).