Agfa Colostar N 42 mm f/4.5
This lens still is kind of a mystery - I don't know exactly what it was used for originally - might have been used in an old Agfa newspaper printing machine. If you know anything please let me know! And if you find a second one of these please do so as well - because so far it's the only one I've ever seen.
You can find a couple more of the sample shots I took with this lens here: https://flic.kr/s/aHBqjzxVaK
and get some information about it and its history in my Agfa article: https://deltalenses.com/index.php/2022/03/21/agfa-enlarger-lenses/