Royal Oak 25554 Perpetual Calendar

In Context

At 39 mm it sits just under the modern norm — the band that suits the widest spread of wrists. The case back is closed, so the movement stays out of sight, and the sapphire crystal will resist everything short of deliberate abuse.

The movement winds itself from the motion of your wrist. 40 hours of reserve carries it overnight, but not through a weekend in a drawer. At 21,600 vph the seconds hand advances 6 times a second, the slower and more audible rate of an older design.

25554ST.O.0344ST.01 stands on its own in this catalogue — no other reference here shares its base number. It pairs a silver dial with a stainless steel case. Beyond the time it carries a perpetual calendar.

Extra-thin movement with perpetual calendar and moonphase; no leap year indicator.