The Langematik Perpetual is the world’s first self-winding wristwatch with an outsize date display and a perpetual calendar the displays of which can be individually corrected as well as collectively advanced. Inside Information: Once correctly set, the date display remains accurate until the next secular year occurs. On February 28, 2100, it will need to be advanced by only one day. The moon-phase mechanism is also stunningly accurate. After 122.6 years of uninterrupted operation, it deviates from synodic lunation by merely one day.