Ian,
I do know that my Ica and Zeiss hollders do not fit---they are too thick. I have three Welta holders which slide in very nicely, but they don't seem to slide all the way to the bottom of the camera. The flocking on the camera and on the holders do line up with each other, but it looks to me as though these holders may leak light. I am waiting for a new batch of film before I can test them, but if you have suggestions on how to choose correct holders, please do let me know. Thanks.