Audemars Piguet Royal Oak Jumbo Extra-Thin Yellow Gold — Openworked Skeleton Dial | Ref. 16204BA.OO.1240BA.01

The Royal Oak Jumbo Extra-Thin represents the purest distillation of Gerald Genta's 1972 vision: a 39 mm octagonal case of extraordinary flatness, housing a movement so thin it redefined what a luxury sports watch could be. This reference in 18-carat yellow gold elevates that legacy further with a fully openworked dial — the Calibre 2121's skeletal bridges and bevelled components entirely exposed, transforming the watch into a study in mechanical transparency. At just 8.1 mm thick, the 16204BA defines what the industry means when it says extra-thin.

Calibre 2121, originally developed in collaboration with Jaeger-LeCoultre as the ultra-slim automatic movement that made the Royal Oak's flat profile possible, beats at 19,800 vph and provides approximately 40 hours of power reserve. In this openworked configuration, its yellow gold bridges and bevelled chamfers are finished to a standard that rivals the finest pocket watches of the 19th century — a reminder that the Jumbo belongs to a tradition of ultra-thin savoir-faire stretching back generations.

The fully integrated 18-carat yellow gold bracelet — with its characteristic flush-fitting integrated design — and the yellow gold octagonal bezel completed with the AP folding clasp create a unified precious metal composition that wears with uncommon elegance for a piece of this technical ambition. A transparent caseback allows the movement's architecture to be appreciated from both sides. For collectors who prize the Jumbo's historical primacy, this openworked yellow gold example is the ultimate expression of the reference's enduring ideal.