This is a Jobo Variformat easel. When used with the Testprinter (sort of an 8x10 step wedge), it basically lets you get a 5 density step wedge over your neg onto paper to help decide printing exposures. I used it for years with a lot of success until I got an RH Designs gizmo that was easier (and far more expensive). There are 4 quadrants and each quadrant can be used for an exposure of 5 densities, so you can make 4 different exposures (you lift one door at a time to do this), expose, dev, check. You can also use 2 doors for a 5x7 or all 4 doors for 8x10, but I always just used a 4x5 square to stretch the paper. The doors are even numbered for numskulls like me who couldn't otherwise keep track of which door was next to expose...
The little manual is included. I found this to be a very useful tool.
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