朗格，精細，18k金自動上弦鏈帶腕錶，配萬年曆、月相及24小時顯示，"Langematik Perpetual"，型號310.221，約2007年製

The Langematik Perpetual is the world's first automatic wristwatch to feature a perpetual calendar, an oversized date and the patented zero reset mechanism allowing the calendar displays as well as the moon phase indication to be advanced either individually or collectively by depressing the calendar change button in the band.

Once correctly set, the date display remains accurate until the next secular year occurs: On 28 February 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.

Lange's patented "zero-reset" mechanism simplifies the synchronization of the watch with a time signal. When the crown is pulled out, it automatically causes the seconds hand to jump to the 12 o'clock or "zero" position.

The Langematik Perpetual model is described and illustrated in A. Lange & Söhne - eine Uhrmacherdynastie aus Dresden by Reinhard Meis, Volume II, 2011 edition, p. 365, pl. 1165.