Zenith El Primero 3604
Grade not disclosed by the source; the edge points at the grade-unknown execution. The brand states a house caliber name and does not name the supplier.
The brand publishes a caliber name of its own and no source in this corpus states which physical design it contains, so this edge sits on the designation rather than on a caliber. The claim is not weaker for it — it is simply narrower than a design.