I had occasion to change the LR44 button cells in a camera, as the battery check showed that they were exhausted. Both cells showed signs of corrosion, so I checked my stock of spares, which admittedly have a use-by date of 2017, only to find every single one showed corrosion leakage in its blister pack. I bought these from a bargain store I think, or maybe the cheapest on e-bay - I can't remember. I know they were past their use-by date but I don't think they should be leaking. I think this is a warning to me, that I should buy batteries from a proven reliable source. I'll stick with the Small Battery Company in future.