After Cartier initially launched their Astrotourbillon movement last year in their Rotonde model, they have carried the mechanics over to the Calibre. The concept of the Astrotourbillon has the balance wheel revolving around the dial once a minute, with the arrow-shaped balance bridge indicating the seconds. In order to make sure that the balance of the mechanism is perfect, a platinum counterweight, which also works to reduce vibrations and shocks, has been added underneath the main dial. In order to protect the delicate inner-workings, the mechanics are housed in a lightweight 47mm titanium casing which gives a slightly sporty touch to the watch. The Calibre Astrotourbillon, or to give it its official name, the Calibre 9451 MC, will be available in a limited run of only 100 pieces, all of which will be individually numbered.