Editorial
The Royal Oak Perpetual Calendar 41mm packs one of the most mechanically demanding complications into a steel sports watch that most brands reserve for precious metal. It runs the 2120/2800, a perpetual calendar module stacked atop the ultra-thin 2120 automatic, and delivers moonphase, day, date, and month on a dial that keeps the tapisserie grid intact. For a steel Royal Oak with a genuine grand complication, this is the reference.
The 26574ST launched around 2016 as a successor to earlier Royal Oak perpetual calendar references in the larger 41mm case format that AP standardized in the 2010s. The movement is the calibre 2120/2800, a periphery-rotor automatic that achieves a 2.75mm movement height before the calendar module -- a genuine engineering constraint given how thin the finished watch sits on the wrist. AP has offered the perpetual calendar in Royal Oak in yellow gold, rose gold, and white gold throughout its history, making a steel reference relatively uncommon and consistently the most sought-after configuration.
The 26574 generation introduced a cleaner layout of the calendar subdials and updated the bracelet finishing to the mix of brushed and polished that defines current production. Production continues today, though AP allocates steel perpetual calendars conservatively relative to total Royal Oak output.
The perpetual calendar module is sensitive to incorrect setting; confirm with any seller that the calendar has not been forced backwards through incorrect crown manipulation, which can damage the mechanism. Ask for service history and confirm the watch has had the movement serviced at an AP-authorized center rather than an independent -- the 2120/2800 requires hands qualified on AP perpetual calendar modules. Inspect the moonphase disc for damage or misalignment, which can occur from magnetism or improper service.
Dial condition matters enormously on tapisserie dials: look for any lifting, cracking at the chapter ring, or refinishing, as AP does not supply replacement tapisserie dials through retail channels. The bracelet on 41mm Royal Oaks of this era develops stretch; check for excessive play between links, especially mid-links, and verify the clasp engages firmly at all positions.
