amanico[JLC Moderator]
400911
Jaeger Lecoultre Odysseus Perpetual Calendar / Master Ultra Thin Perpetual Calendar 39.
Circa 30 years separate the Odysseus perpetual calendar, which is the ancestor of JLC Perpetual Calendars, in platinum:

And the Master Ultra Thin perpetual calendar, unveiled in 2013, here in steel:

Two different ways to display the perpetual calendar, the years, the danger zone.
The case changed a lot, too, more sober on the Master Ultra Thin, more elegant, in my opinion, too.
But still, an indisputable air de famille between these 2.
Enjoy,
Nicolas