||The 1/87 is one of the most common
Faber-Castell slide rules. Remarkable of this one is that it has a
celluloid cursor, instead of the normal aluminium with glass one. I
first thought that the cursor came from one of the cheaper school slide
rules. It fits perfectly though. Another explanation might be that at
the end of WW-II there was a aluminium shortage, so-that they were
forced to use celluloid.
I have another 1/87
from January 1946 (catalog number 53) that shows some remarkable
differences from this specimen: it has a metal cursor, the extensions of
the ABCD scales and the I scale are printed in red and it has a 1:25
scale on the bottom side.