Royal Oak Extra-Thin Stainless Steel / Silver

In Context

At 39 mm it sits just under the modern norm — the band that suits the widest spread of wrists. At 8.1 mm thick it is about average for a modern wristwatch. The case back is open, so the movement is visible without taking the watch apart, and the sapphire crystal will resist everything short of deliberate abuse. 50 m covers rain and hand-washing comfortably; it is not a watch to swim in.

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.

15202ST.OO.0944ST.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. Introduced in 1972.

The 2121 is the ultra-thin automatic of the original Royal Oak, 3.05 mm high. It is built on the Jaeger-LeCoultre 920 base that Audemars Piguet, Vacheron Constantin and Patek Philippe all used. It powers 23 watches in this library. Jaeger-LeCoultre designed the 920 in 1967 for its three clients, and it is the reason the 1972 Royal Oak could be 7 mm thick with a full-size rotor: the rotor runs on a rail around the movement's edge on four ruby wheels, and there is no ball bearing to add height. Audemars Piguet's version, the 2121, runs at 21,600 vph with 36 jewels and a 40-hour reserve at 28.4 mm across, and it powered the Royal Oak "Jumbo" from the 5402 of 1972 through the 15202 until the in-house 7121 replaced it in 2022. In the library it powers 23 [Royal Oak](/brands/audemars-piguet/royal-oak) references, the 15202 Extra-Thin in steel, pink gold, white gold and platinum and the 15201 anniversary edition, 22 of them at 39 mm. 8 are limited editions. The [2120/2802](/calibers/audemars-piguet-ap-2120-2802) is the same base with a perpetual calendar, the Vacheron Constantin [1120](/calibers/vacheron-constantin-1120) the sister version, and the [3120](/calibers/audemars-piguet-ap-3120) the thicker in-house movement of the 41 mm Royal Oak.

22 other watches in the library run the Audemars Piguet AP 2121.

Audemars Piguet

Royal Oak 15128 Jumbo Italia

15128ST.OO.0944ST.01 · 39 mm

Audemars Piguet

Royal Oak 5402 Jumbo

5402ST.OO.0344ST.01 · 38 mm

Audemars Piguet

Royal Oak Extra-Thin The Hour Glass

15205BA.OO.1240BA.01 · 39 mm

Audemars Piguet

Royal Oak Extra-Thin Pink Gold / Silver

15202OR.OO.0944OR.01 · 39 mm