The Audemars Piguet Royal Oak ref. 5402 is the original Royal Oak reference, introduced in 1972, pioneering the concept of a luxury sports watch with an integrated bracelet and an ultra-thin automatic movement. Designed by Gérald Genta, the watch was initially produced exclusively in stainless steel, setting a new standard for high-end watchmaking. Due to its 39mm case diameter, which was considered large for its time, it became known as the "Jumbo".

In 1977, Audemars Piguet introduced the 5402SA, a refined two-tone version combining stainless steel and 18k yellow gold. This model remained significantly rarer than its steel counterpart, with only 876 units sold, numbered from 1 to 951. With serial number 109, this example is an early production piece within the 5402SA series.

This watch is powered by the Caliber 2121, an ultra-thin automatic movement based on the Jaeger-LeCoultre 920. Measuring just 3.05mm in height, it remains one of the thinnest full-rotor automatic movements ever produced.

The dial features the petite tapisserie pattern, a defining characteristic of the Royal Oaks. The "Swiss Made" marking at 6 o’clock suggests the dial was either part of a later production batch or refreshed after the mid-1980s.

Originally sold on March 30, 1979, this watch is accompanied by its original box and guarantee papers, which are rarely preserved with early Royal Oaks. It has also undergone a full service in 2023. As the first Royal Oak reference and a rare two-tone variant, it holds an important place in Audemars Piguet’s history.