The Leonidas 121 watch movement, which was manufactured between 1898 and 1918, is an open face calibre with a bimetallic screw balance that features four adjustment screws. The watch and alarm are driven by a single barrel, and the alarm wheel with setting hand is situated on the dial. Additionally, the movement incorporates a ratchet on the dial side along with a crown mechanism that utilizes a single-arm rocker bar. Furthermore, this movement offers the functions of stem winding and pin setting for the alarm, as well as a sub-second display.