Behold the first Jaeger-LeCoultre calibre to associate a tourbillon with a perpetual calendar. Comprising of exactly 401 parts, this fascinating watchpiece is constructed on a split-level structure.

The dial is divided between an upper part displaying the hours and minutes as well as the perpetual calendar indications, and a "dropped"/lower part to allow the tourbillon to look distinct and separate. The large 11.5 mg.cm2 variable-inertia balance is equipped with adjustment screws around its rim in order to ensure the long-term constancy of a rating that remains unaffected by impacts.

Oscillating at a rate of 28,800 vibrations per hour, this is indeed a high precision equipment. The lever features a more compact shape that results in significant energy saving, since it brings the escape-wheel closer to the centre of the tourbillon.

The watchmakers and engineers at Jaeger-LeCoultre have set the finishing touch to this accomplishment by using a grade 5 titanium carriage which is so light that it enables them to create a 78-part tourbillon escapement weighing a mere 0.28 grams. A genuine masterpiece of innovation, the perpetual calendar displays the date, day of the week and month, while automatically taking account of the length of the months and the leap-year cycle.

To achieve this feat, the movement must be endowed with a mechanical memory of 1,461 days, meaning exactly four years. Its complexity is such that it requires several hundred parts composing the various gear trains and levers. Finally, the movement is equipped with a lubricant-free unidirectional rotor, since tests conducted within the Manufacture have shown that winding in a single direction is in fact more efficient than bidirectional winding.