I present to you, the most photographed film holder on earth! :D
Seriously, though, what does this fit? Width 100 mm, length 150 mm up to the insertion point of the darkslide, thickness 4 mm. The lip on the lower part of the holder is 9 mm long. Otherwise, I guess the photos says it all.
Is this what is known as Universalfalz? The holder takes 9x12 cm film.