I have had this 11x14 Eastman 2d camera for a few decades, but never noticed this before. Just starting to use it more extensively. The ground-glass back has a velvet like "seal" that the film holder rests on when inserted, unlike many other (smaller) LF cameras where the film-holder has to form a light-tight seal against wood. I wonder if this is due to the possibility that 11x14 holders being so large that there might be some minor warpage??..thus the "cushion" of the velvet helps make a seal? I have 4 11x14 double dark slide film holders. They are all constructed the same, and look just like "scaled up" 8x10 or 4x5 holders. Now on 8x10 or 4x5 one inserts the holder and a locater ridge on the holder drops into a groove in the camera ground-glass back. This serves two purposes (as I see it), 1. it indicates to the photographer that the holder is fully inserted. 2. It helps retain the holder in the camera when you pull the dark slide. Well, I just noticed the Eastman 11x14 2d does not have the groove. The velvet facing is smooth no groove. The holder slides in fine, but one has to stop with the locator ridge resting just outside the back. On the 11x14 holders I have this ridge is right at the edge anyway, just before the dark-slide pulls. I have used my holders and this camera with no problems this way, but I still wonder..... My question: The Eastman 2d is a relatively "late" wooden 11x14 camera. Did it require any "special" holders in general? I believe my holders are "Eastman" brand, thus should be quite compatible, and of course they do work just fine, but the locater ridge/groove thing is confusing to me in regards this camera. Does anyone else have one of these and can comment?