They look like the same 9x12 holders my Voigtlander Avus uses. More importantly, that means they are the same size as the old Soviet Fotokor. I was able to order mine from a Ukranian dealer I had done business with on eBay. He didn't have any listed (I think the possibility that someone would be looking for plate holders was a surprise), but was able to find some. They needed cleaning, but were cheap.