This is the lock knob used to secure the LPL00672 red filter assembly in the lens stage of LPL, Saunders/LPL, and Omega/LPL 4x5 enlargers. The same screw is also used as the lensboard securing screw in LPL 7700, and Saunders/LPL and Omega/LPL 670XL enlargers.
Please note that this is not the correct red filter securing screw for LPL 6600, 6700, and 7700 enlargers - see item #LPL3231-186.
