Thank you for your interest. The holders are for an ICA Klappreflex-Kunstler camera. I've never actually seen one but I obtained the model number from an individual who had one of these cameras. I suspect that they are double sided and quite similar to other ICA and Zeiss holders of the period (737/12 for 10x15cm, and 737/6 for 9x12cm Juwel, if you are familiar with any of these). My camera came with a film pack holder. The dimensions of this holder are 11x17.5cm overall. The "face" of the holder is 11x17cm. The long sides have approx 2mm wide x 2mm deep "edges" that fit into corresponding slots in the camera back. The holder slides in and is secured by a "catch" that fits into a small cut-out in the top of the holder approx 3cm from the rear edge. I would post some photos but I haven't yet got on the digital bus.....