Unknow plate on process lenses

[Ginette]

I put some process lenses in the For Sale section mounted on theses plates 7" diameter.

Are theses plates for a particular process camera, enlarger or what?
Maybe it have no value (more value in recycling metal!)

Thanks for the info.

[Ginette]

Wow, more than 600 views and no one know?
I look at all "lensboard" and all "process" on *bay and see no one like theses. Also look in Google images with no results. Is it a better search term?
Omega made lensboard with keyholes but in 3", I think. Did they do 7" too?

Look like no one need theses plates. Maybe it will be better to discard the plates and sell the lenses alone?