This Durst 6 3/4'' horizontal enlarger lens board has a 44mm threaded opening. It is for use with Durst HL 2500, 2501, and HL2506 enlargers. It has scuffing, scratching, and discoloration on its exterior (please see photos).
Durst
Durst
Sinar
Schneider
Kodak
Schneider
Rodenstock