This is the IWC Eternal Calendar. A secular perpetual watch so complicated, in its mechanical complications, that even without a need of an electronic calculator can keep an accurate perpetual moonphase with 45,000,000 years accuracy and a calendar accurate until 3499ad. Simply outrageous and I have held such a contraption in my hands about a month or so ago at an IWC x Tatler GMT event at its boutique at the Pavillion Kuala Lumpur.
