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Bracelet with oysterlock have a shorter screw at this position. It's because this screw don't go through the metal on oysterlock bracelet, and it go through the metal on bracelet without oysterlock like 72200/72600 .
I am not sure I am clear as a I don't know the English word for "affleurant"
As a example, Here are 72600 side by side with bracelets with shorter screw 32-20638:
