This slide rule is still sealed. Sealing clearly turns color toward yellow and degrade a bit.
But slide rule should be intact. So oxidation is highly unlikely. Please enjoy looking at photos. Faber Castell 67/87 Rb Slide Rule RIETZ Collectable SEALED Addiator" is in sale since Thursday, September 19, 2019.
This item is in the category "Collectibles\Science & Medicine (1930-Now)\Engineering\Slide Rules". The seller is "trpkovesn" and is located in Belgrade, default.
This item can be shipped worldwide.