I have 4 lens boards that I got with my DeVere 504, they do not fit the larger format DeVere's. The locking collar is 72mm/6.5" in diameter The recessed boards are 2" and 4" deep. The recessed boards have an orientation notch in the collar. The 2 flat boards do not. There is the number 2969 stamped on the back of the flat board, but no number on the recessed. They are very well made, more in the Durst-DeVere genre than the Beseler-Omega.
Any thought would be appreciated.