I am familiar with the mercury batteries sold from Russia. They are ~1.35V mercury cells, they are made well, no leakage, tight. The outside needs to be roughed up a bit for use, they have some kind of matte looking skin on them that does not conduct well. I actually just recently noticed that they are not the same shape as the old 625 cell. Was trying to put the battery into a Leica M5 and the cover cap would not engage the threads. Upon closer inspection, the negative side, which is the one that has both poles on it, is not tapered like the original battery or like the wein cells. There is a ridge present from the material that keeps the 2 halves of the battery separate. So, there are some installations that just will not work. The material can be carefully trimmed to get the battery shape closer to the proper taper, but it really never gets too close to the original shape. And doing any trimming, filing, or sanding is really not the best practice on something with Mercury inside it. I believe the best solution to the 625 battery replacement problem is still the MR9 adapter loaded with a silver cell. It's just too bad the prices of these has never really come down over the years. The price is sometime higher than the worth of the old cameras and meters.