Product Information
* Factory: ZF Factory
* Brand: Audemars Piguet
* Collection: Royal Oak
* Reference: 15500ST.OO.1220ST.02
* Case Size: 41 mm
* Dial: Grey Dial
* Case / Bracelet: Full Steel
* Movement: 4302 Automatic Movement
* Crystal: Sapphire Crystal
Technical Specifications
* Measured Case Width: 41.0 mm
* Measured Case Thickness: 10.6 mm
* Measured Weight: 170.6 g*
* Movement: 4302 Automatic Movement
* Beat Rate: 28,800 BPH
* Crystal: Sapphire Crystal
*The 170.6 g weight is the actual measurement of the individual watch inspected. Bracelet sizing, production tolerances and individual assembly may result in minor differences between watches.
Timegrapher Test Results
* Daily Rate: +11 Seconds/Day
* Amplitude: 247°
* Beat Error: 0.2 ms
* Beat Rate: 28,800 BPH
Testing Note
These readings were recorded from this individual watch during its pre-shipment QC inspection.
Mechanical movement readings can vary according to power reserve, watch position, temperature and testing conditions. The recorded +11 seconds/day represents the movement’s performance at the time of testing rather than a permanently fixed daily rate.
For this inspection, the +11 seconds/day result remains within the QC reference range. Movement condition should still be evaluated together with amplitude, beat error and actual functional operation.
4302 Automatic Movement Performance
This ZF Factory Royal Oak 15500ST is equipped with a 4302 automatic movement operating at 28,800 vibrations per hour.
The recorded results were:
* Daily Rate: +11 Seconds/Day
* Amplitude: 247°
* Beat Error: 0.2 ms
* Beat Rate: 28,800 BPH
The recorded data showed acceptable operation under the testing conditions.
In addition to the timegrapher results, pre-shipment inspection should include automatic winding, manual winding, crown operation, time setting and date adjustment.
41mm Case, 10.6mm Thickness and 170.6g Weight
The individual watch inspected measured:
* Case Width: 41.0 mm
* Case Thickness: 10.6 mm
* Measured Weight: 170.6 g
These measurements provide practical reference data for the actual watch rather than relying solely on nominal specifications.
The combination of a 41 mm case, 10.6 mm measured thickness and 170.6 g full-steel configuration gives the watch a substantial wrist presence while maintaining the relatively slim profile associated with the Royal Oak case design.
Grey Dial Inspection
The grey dial is one of the most visually important parts of this 15500ST.OO.1220ST.02 configuration.
Because the Royal Oak dial contains a highly structured surface pattern, small inconsistencies can become visible under close inspection.
QC should therefore focus on:
* Dial texture consistency
* Grey color presentation
* Hour-marker positioning
* Logo and text printing
* Hand alignment
* Date-window positioning
* Date numeral centering
* Surface cleanliness
The dial should also be inspected under different lighting angles because its visual appearance can change depending on reflection and viewing conditions.
Full-Steel Case and Bracelet Finishing
The Royal Oak uses a combination of brushed surfaces, polished edges and sharply defined transitions. These finishing details are particularly important because the integrated bracelet forms part of the overall case design.
Important inspection areas include:
* Bezel brushing
* Polished bezel edges
* Bezel screw alignment
* Case brushing
* Surface transitions
* Bracelet-link finishing
* Bracelet articulation
* Case-to-bracelet integration
* Clasp operation and locking
On the individual watch inspected, the overall finishing and assembly showed a good level of consistency.
Sapphire Crystal Inspection
The watch uses a sapphire crystal.
During QC, the crystal should be inspected for clarity, surface condition, installation, alignment and any visible scratches or edge damage.
The crystal should also provide a clean view of the grey dial without obvious installation-related distortion or contamination.
Version Development and Current Position
The ZF Factory 15500ST has undergone multiple version updates over its production history, with attention given to areas such as movement configuration, case proportions, dial presentation and exterior finishing.
The current version benefits from this continued development and is one of the stronger 15500ST versions currently available for comparison.
Rather than describing any version as universally the “best,” the more useful approach is to evaluate the actual watch through measurable and visible factors such as:
* Movement test results
* Case dimensions
* Dial execution
* Bezel and screw alignment
* Case finishing
* Bracelet construction
* Overall assembly
Based on this individual QC sample, the current ZF version demonstrates advantages in several of these areas and is a version worth comparing when evaluating the 15500ST.
QC Observations
This ZF Factory Audemars Piguet Royal Oak 15500ST.OO.1220ST.02 recorded:
* +11 seconds/day
* 247° amplitude
* 0.2 ms beat error
* 28,800 BPH
* 41.0 mm measured width
* 10.6 mm measured thickness
* 170.6 g measured weight
The 4302 automatic movement showed acceptable performance under the recorded testing conditions.
From an exterior perspective, the grey dial, steel case, bezel, integrated bracelet and overall surface finishing showed a good level of consistency on the inspected watch.
The current ZF version has benefited from several stages of development, and the inspected example demonstrated a balanced combination of case proportions, movement performance, dial presentation, bracelet construction and exterior finishing.
It can therefore be considered one of the stronger versions currently available for this reference. Individual QC remains important, however, because movement readings, alignment and finishing can vary between watches and production batches.
Pre-Shipment QC Inspection
* ✔️ 4302 automatic movement checked
* ✔️ Timegrapher readings recorded
* ✔️ +11 seconds/day rate documented
* ✔️ 247° amplitude recorded
* ✔️ 0.2 ms beat error recorded
* ✔️ 28,800 BPH beat rate confirmed
* ✔️ Automatic winding function checked
* ✔️ Manual winding function checked
* ✔️ Crown operation checked
* ✔️ Time-setting function checked
* ✔️ Date adjustment and switching checked
* ✔️ Case width measured at 41.0 mm
* ✔️ Case thickness measured at 10.6 mm
* ✔️ Individual watch weight measured at 170.6 g
* ✔️ Sapphire crystal inspected
* ✔️ Grey dial surface inspected
* ✔️ Hour-marker and hand alignment checked
* ✔️ Date-window alignment checked
* ✔️ Bezel finishing inspected
* ✔️ Bezel screw alignment checked
* ✔️ Case brushing and polished transitions inspected
* ✔️ Integrated bracelet articulation checked
* ✔️ Bracelet-to-case integration inspected
* ✔️ Clasp locking function checked
* ✔️ Overall exterior assembly inspected
* ✔️ Final pre-shipment QC inspection completed
