chamonix 4x5 04N2 knob

[esearing]

What is this odd round knob at the top of the rear standard? black circle with a hex head screw. Doesn't seem to have any purpose.

 

[Ai Print]

You loosen them to release the bellows from the rear standard, for example, when going from the universal bellows to bag bellows for short lenses needing a lot of movement.