Jaeger-LeCoultre SS AUTOMATIC SHELL ST

The watch presented here is powered by the hand-wound Caliber 900, a movement sourced from the ébauche manufacturer A. Schild (AS).

During the 1970s, the watch industry faced two major challenges: the Oil Crisis and the rapidly approaching Quartz Crisis. In response, many traditional manufacturers were forced to rethink their strategies. Caliber 900 was born from this turbulent period — a product of its time in which brands, while reluctantly stepping away from the strict ideals of manufacture watchmaking, focused on achieving a balance between cost efficiency and reliable performance.

Operating at 21,600 vibrations per hour, the movement offered a higher beat rate that provided improved accuracy and reliability. This combination of precision and cost-performance became one of the key weapons used by traditional watchmakers to navigate the difficult transition of the era.

The watch itself also reflects an important historical concept in case construction. Its caseback is secured by four screws, a design whose origins can be traced back to 1930, when Schmitz Frères & Cie developed a method of constructing a case from two shell-like components joined together and secured with four screws. By fastening the two case sections in this manner, the design significantly enhanced water resistance.

This concept was later further developed when Gallet acquired the rights to the design, ultimately resulting in the patented system known under Patent No. 189190.

The case of the present watch carries the genetic legacy of this construction philosophy. Crafted from stainless steel, it features a distinctive hexagonal four-screw case designed with water resistance as its primary objective.

A recessed section in the case allows the crown to sit partially embedded within the case structure, further protecting it and enhancing the watch’s resistance to water ingress.

The result is a watch whose design reflects a consistent pursuit of durability, functionality, and engineering ingenuity — a true product of its era and a fascinating chapter in the history of tool watch construction.

- wrist size in our picture is 17cm circumference -