The Manufacture Calibre MT5641 was developed by TUDOR specifically for the Glamour Double Date model. For the first time, a TUDOR Manufacture Calibre has a small seconds hand at 6 o'clock as well as a double date function at 12 o'clock. The Calibre MT5641 has an openwork rotor that is satin-brushed with sand-blasted details and its bridges and plate have alternate polished sand-blasted surfaces and laser decorations. Its build is designed for robustness, longevity and reliability, as is its variable inertia balance held by a solid double anchor bridge. Coupled with a non-magnetic silicon spiral, the MT5641 Calibre is certified by the Swiss Official Chronometer Testing Institute (COSC), with a precision going beyond the criteria of the institution of -2 +4 seconds per day, and it has a 70-hour power reserve.