Ok sorry, without looking it up I might have described it a bit stupidly. So I took a photo strictly following "a picture is worth a thousand words". And I also measured again right away. The passage is 73cm wide, the narrow part at the front right (called "corner piece" by me) is 26cm and the depth of the shower is 120cm. This 26cm "corner piece" had to go on this side, otherwise maybe water would have gotten on the wall there. We would have preferred it on the other side, as possibly the pipe above would have been omitted then. Unfortunately, the owner did not build the shower flush with the floor here, but it works perfectly and no Mediterranean Sea is created outside. Anyway, with almost every shower some water gets outside, for example with doors when they are opened and water drips off. We are less bothered by a few drops on the floor. So THAT would be my minimum size, although I would prefer 140cm and then without a "corner" and as I said half-high built.