I have a few questions about Kodak 5X7 Plate Holders. I tried to do a search, but nothing comes up. I have three of these plate holders and I am not too sure how they are used. They seem to have the ability to hold a plate on either side of the holder. The inside seems to have a plate size reducer?
I also have an 8X10 Bromide Plate, that only has the ability to hold a plate on one side. The back is hinged. The plate holders are made by Graflex for Eastman Kodak.
Any info would be appreciated.

Jose