I have a 9x12 Perka, similar to yours Steve. I think they were also sometimes known as Plasmat cameras. I can't find that reference now, but I also tried finding information about the camera after I bought mine. Mine has a 15.3cm Meyer Plasmat, 32cm / 22cm cells. I guess yours is triple extension too? I don't know, but guess your camera might originally have had a convertible plasmat lens too. The extensions on my camera are set up to match infinity focus for the different cells, it's a great camera. There were (maybe still are) a few Meyer Plasmat lenses on ebay that I think got pulled out of Perka cameras.