This is an Agfa Isolette I, the first in a series of Isolette cameras, all built on the same frame, from Agfa. Isolettes had two big problems. The first was that they used a vinyl coated cardboard for the bellows and it typically developed pinholes after about a year (or even less). The other was that they used a cheap grease to lubricate the focusing helicals that had no galvanic resistance. This was a problem because the top cap is chromed brass. The two different metals, chromium and brass, in direct contact with one another reacted and generated a very slight electrical current. It wasn't much at all, but over decades, it caused the grease to polymerize and form molecular chains of what is essentially a type of plastic. The result of all this is that the front and center lens elements, which screw together and apart to focus, are stuck together on nearly all of the older cameras with a green substance that is about the same consistency as road tar. If you are patient, you can soak the lens elements apart with alcohol over about two weeks or a month; if not, the only thing that will soften that gunk enough to force it loose enough to turn is heat. If you look in my journal, under really REALLY bad camera repair ideas, you will find a number of stories about people who didn't know what to do who attempted to repair Agfas. They are good cameras, were popular and are exceptionally easy to screw up. Well, this one has a set of "new old stock" Kodak replacement bellows (really meant for a Kodak 66, but a perfect fit) and the old grease has been removed and replaced with a much higher grade grease. It has been cleaned, lubricated, adjusted and works perfectly. 6x6 replacement bellows from Zeiss and Balda will also fit, but the bellows from Weltas will not, since they used a differently sized shutter and so they are made to fit a larger front standard. All things considered, the Kodak bellows are probably the best bet, since bellows were one of the few things Kodak did really well, they are usually less expensive (because the rest of a Kodak 66 was crap), and they are robust enough to give you many years of service.