



The black area on the bottom of the lock says "C&K (2) USA F SERIES". A quick search on google gives me the impression that C&K is a switch company that also makes keyswitches, so it is possible that they licensed the mechanism from someone else. There is a notch on the key which may point to a side bitting like the Duo, and it kind of looks like there is a wafer near the front that is lifted by this. The lock came from an old mainframe computer, I think it was an IBM (system/36 maybe?) which was old enough that they went two for $5 when I bought them in '97.