One more thing: The holders are all marked 665/7 and Zeiss Ikon, though there are a few slightly different designs. There are seven of them, plus a Voigtlander holder that appears to be for a film pack or something similar.

The two diopters are marked Carl Zeiss Jena, and Proxar 2 x 42 and Distar 3 x 42. The yellow grad filter has no markings, and does not appear similar in design to the Zeiss diopters.