CHPTR_Δ (Chapter Delta) is adorned with an elegant two-tone combination, pairing steel with a yellow gold PVD coating. This fusion of materials offers a look that is both classic and contemporary.

CHPTR_Δ is the first BA111OD manufacture watch complication: a unique timepiece that represents time in a revolutionary way. 

Rather than simply rotating a hand around a central axis, the movement was designed to "roll" a satellite hour wheel around a fixed central hour wheel. When a wheel is rotated around another wheel, the trajectory described by any point on this satellite wheel is a cycloid. There are several types of cycloids: in this BA111OD chapter, the chosen cycloid is a deltoid (with a ratio of 1/3), and as a result, the trajectory described by the tip of the hour hand is... a triangle.

Created with the help of renowned watchmaker Olivier Mory, CHPTR_Δ's asymmetrical reading of time is a world premiere that promises to captivate and inspire anyone who seeks a new and unique way of reading time.