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Finally! I have found both the razors and the key to unlock them. I had put them in separate places.
It took me 3 days of looking to get them together again.
The key is inserted into the bottom of the handle then turned to the left to remove the razor's head. Then a new blade can be inserted.
At least it was an attempt to keep the prisoners from slicing each other's throat.
OMG - I never knew such razors existed!
In retrospect, they make sense. How did you ever get your hands on them or, maybe I should ask your lawyer?