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THE MILITARY SUBMARINERs were adapted following the specifications requested by the British Ministry of Defence as part of the equipment of some military corps. The watch cases were soldered with fixed bar lugs, the dials easily readable and were therefore equipped with "sword"-type hands. They also had to show the international symbol for tritium - the encircled "T' for the presence of tritium in the luminescent coating of the hour markers.
On the case back one would find a series of engraved markings:
0552 corresponds to the British Ministry of Defence
923-7697 corresponds to the NATO code
the Broad Arrow characterises all watches owned by the British Army
680 is the issue number and 77 indicates the issue year.