The Vest Pocket Model B took 4x6,5cm photos on 127 film. The lens in mine is a Doublet f8, fix focus. The camera has to be loaded through the front side, after removing the whole bed and bellows unit, which is a pain! The camera has the "Autographic" window on the back, that could be used to scratch notes into the backing paper of the autographic film. The notes were burnt into the film by the sunlight, some early version of a data back.