With its development starting in the 1920s, the Longines in-house chronograph caliber 13ZN, is arguably one of the most beautiful chronograph movements ever developed. This legendary manual wind chronograph was in production until the beginning of the 1970s.
Appointed the official supplier for the International Aeronautical Federation (IAF) in 1919, Longines was a pioneer in making a wide variety of watches for pilots and military personnel, most notably the Weems and Lindbergh models. In order to keep track of their military issued watches, they created serial codes for each pilot that was given a watch.

Scholarship tells us that the present single-button chronograph was made for a Romanian military pilot, Sireteanu Alexandri from the M.A.M. (Ministry of Air and Marine) unit in 1937. The black dial features large luminous Arabic numerals and hands, while the rotating bezel is also fitted with a luminous triangular arrow for clear visibility during night flights. Interestingly, this chronograph is one of the earliest models ever made with a revolving bezel.

The present watch is an excellent, original example of a large vintage Longines chronograph, further enhanced by its rarity and superb condition. Fitted with the legendary 13ZN, the case and movement number are perfectly matched. This watch is believed to be one of only so many made, and is sure to make a great addition to any collection of fine timepieces.