This is a highly rare Longines chronograph from the early 1940s, featuring the renowned Cal. 13ZN movement, housed in a scarce 34mm three-piece waterproof case. Produced during the transitional period when Longines was experimenting with waterproof chronographs, this model consists of a bezel, middle case, and screw-down case back.
The unique case design and proportions—characterized by a 34mm stepped case, round pushers, and a rounded case back—set it apart from other Longines waterproof chronographs such as the "Mushroom," "Tretake," 35mm snap-back waterproof models, and 37mm "Lip" variants. Despite its modest size, this watch exudes the signature heft and presence that Longines is known for.
Longines’ in-house chronograph calibers are recognized as masterpieces in horological history, having firmly established their reputation over time. This legacy is expected to endure for generations.
Included is an original Longines buckle from a later period. Notably, this Cal. 13ZN example is an unusual variant without the flyback function, making it an exceptionally rare find.