The Rotating Seconds Sub-Dial: A Mechanical Signature. Among the Oslo Theorema’s distinctive technical features, the rotating seconds sub-dial stands out as its most identifiable signature. Unlike conventional sub-seconds designs that use a static dial and a sweeping hand, the Oslo’s entire sub-dial rotates—an inversion of the traditional display. From an engineering standpoint, this requires a differential gear linkage between the fourth wheel and the rotating disc, ensuring stable rotation without excessive drag. The result is not only visually captivating but mechanically intriguing: a kinetic reminder that motion can be displayed in multiple languages of mechanics. Collectors have long appreciated this feature for what it represents—innovation within the framework of tradition. It’s an uncommon complication not found in mainstream automatic watches, particularly at this level of craftsmanship. The sub-dial, finished in deep navy with concentric guilloché, is anchored by two exposed screws, symbolizing its integration into the movement rather than as an applied module. Tap photo or visit tufinawatches.com #mechanical #automaticwatches #mechanicaldesign #mechanicalengineer #tufina