Audemars Piguet
Royal Oak Offshore Selfwinding Chronograph
Ref. 26238ST.OO.2000ST.01
2021–present · 42mm · caliber AP Cal. 4404: in-house automatic flyback chronograph, column-wheel, vertical clutch, 28,800bph, 70h PR, 381 parts; used in the 2021 Royal Oak Offshore Selfwinding Chronograph relaunch
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Movement tier: unclassified
Medium-large: suits wrists 6.5 in+ (16.5 cm+)
42 mm case. Wears confidently on average to larger wrists. May overhang on slender builds.
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Authentication
The interchangeable strap system is reference-specific; the steel bracelet and rubber strap both use AP's tool-free quick-release, not generic spring bars.
Known issues in the market
- Aftermarket rubber straps sold as "AP-compatible" lack the correct quick-release tab and lug-fit; only the AP-supplied blue rubber strap matches this reference.
- Cal. 4404 is a flyback; confirm a single pusher press resets and immediately restarts the chronograph rather than the two-step stop-reset-start of a standard chronograph.
| Area | What to check | What is correct | Red flag |
|---|---|---|---|
| case | Screw-locked crown and rubber-clad pushers | Crown screws down fully with consistent thread feel; pushers are blue rubber-coated and depress smoothly | Crown that cross-threads or will not seat; pushers with cracked, missing, or mismatched rubber coating |
| dial | Blue Petite Tapisserie pattern and registers | Fine-grid Petite Tapisserie (finer than the Mega Tapisserie used on Offshore Diver models) with tone-on-tone blue chronograph counters and white gold applied indices | Coarse Mega Tapisserie grid inconsistent with this reference; counters or indices in the wrong finish |
| movement | Cal. 4404 flyback behavior | Single-pusher flyback: instantaneous stop-reset-restart with no hesitation; 70h power reserve on a full wind | Two-step reset sequence typical of a non-flyback movement swap; power reserve well short of 70h |
Common legitimate replacements
- The quick-release bracelet and rubber strap are reference-specific AP parts; generic spring-bar straps will not seat correctly in the lug.
- Cal. 4404 is in-house; no third-party equivalent exists.
Expert resources: AP Royal Oak Offshore documentation at audemarspiguet.com. WatchUSeek AP forum for Cal. 4404 flyback function testing.
