The International Durowe 391-4 watch movement, in use around 1915, incorporates several notable features and functions. It features the hunter calibre and is equipped with a bimetallic screw balance and an optional balance with four adjustment screws. The movement utilizes a Breguet hairspring and is regulated by a cam disc regulator. For the US market, it incorporates a negative stem mechanism. In early samples, it clicks open face, while in later versions, it features a regulator similar to the Zenith 16'''. The stem mechanism design is based on Swiss Patent 30751, filed on May 19, 1904, by Georges Favre-Jacot & Cie. The movement includes the functions of stem winding and setting, as well as sub seconds.