The North Flag is one of the first TUDOR models to be fitted with a TUDOR Manufacture Calibre. Visible through a sapphire crystal in the case back, the movement presents matt finishes, emphasising its precision, reliability and high level of technology through large surfaces that have been sand-blasted, embellished with details or sunray-brushed, and an open worked central rotor.
This movement provides impressive autonomy. Its power reserve of approximately 70 hours means that its wearer can, for example, take off the watch on Friday evening and put it on again on Monday morning without having to wind it. Beating to a frequency of 28,800 beats/hour or 4Hz, the movement is regulated by a variable inertia oscillator with silicon balance spring, held in place by a traversing bridge fixed at both sides to improve resistance to shocks and vibrations. Its self-winding system is bidirectional. The movement is certified by the Swiss Official Chronometer Testing Institute (COSC).