Good afternoon to all fellows. I have recently purchased some NOS single exposure plate holders to fit the single exposure back attachment of the mamiya C twin-lens-reflex. These holders can hold a glass plate or, with the interposition of a tin adapter provided with each holder, a sheet of cut film. I do not understand, however, which kind of format these are intended for, as standard 6x9 cm film sheets proved too big to fit into the guides. Was a format of sheet cut film smaller than 6x9 cm once available, perhaps? Did anyone devise a clever modification to the sheet adapter to have it fit standard 6x9 cm sheets, without the need of filing away the metal guides, end rivets and such? Thank you very much.