Casio G-Shock DW002, ca. 1996

Note those two gray flaps...
They rotate ca. 45 degrees outward to accommodate larger wrists. The design is really great! They seem to be spring loaded. But if you look closely, you can see that the shape of the two flaps' rotational axes is eccentric. And that eccentric shape rubbing against the gray back protection of the watch creates the impression of spring loaded flaps that immediately return to the position in this picture. A great way of stabilizing a high watch on the wrist.