Lange 1 Tourbillon Perpetual Calendar is a luxury wristwatch by A. Lange & Söhne.

The watch is an evolved version of the famous Lange 1 model, combining two sophisticated complications, the tourbillon and the perpetual calendar. The characteristic decentralized dial design of the Lange 1 has been retained and subtly enhanced so that it does not look cluttered and remains easy to read.

Contributing to this is the new, patent-pending invention of the month display via an external rotating ring.

All displays of the perpetual calendar – big date, retrograde day of the week, month ring, leap year and moon phase indication – advance jumping and are thus easily readable at any time.

In order not to disturb the dial design, an opening for viewing the tourbillon was omitted (until now, an understatement philosophy known almost only from Patek Philippe). This can be admired through the glass back. It should also be mentioned that the tourbillon can be stopped with a patented, extremely practical stop-second mechanism to precisely set the seconds indication.