The Three Crowns (Cat's Paw): the Swedish Gold Hallmarks, sometimes known as the "cat's paw" (kattfot), signifies that the piece meets the legal standard for gold.

Early examples of the Ref. 1803 were fitted with the upgraded calibre 1555, featuring a free sprung Micro-Stella balance but lacking a quickset function. Adjusting the weekday and date required advancing the hands past midnight repeatedly until the correct indications were reached.

By the mid-1960s, the movement was updated to calibre 1556, which operated at a higher frequency of 19,800 vibrations per hour and included an additional jewel, bringing the total to 26, though it still did not offer a quickset mechanism. In 1972, the calibre 1556 received a further improvement with the addition of a hacking function, allowing the seconds hand to be stopped for more precise time setting.

These movements marked the first fully in-house calibres used in the Day-Date, replacing earlier outsourced mechanisms.