The Must de Cartier line, created by Robert Hocq and Alain-Dominique Perrin, aimed to attract new customers by offering accessories and leather goods with the essence of Cartier. The Must de Cartier Tank wristwatch was the brand's most iconic item, made from sterling silver with a minimum of 10k plating at 2.5 microns thick. Launched in 1976, the line marked key milestones for the brand, including being the first non-precious metal watch and the first mass-produced watch. The brand produced around 3000 watches per year before the Must Line, and by the end of the 70s, they were producing over 160,000 watches per year. The dials varied, with faux-stone dials resembling onyx and lapis, lacquer dials in wood and tortoiseshell, and the Trinity dial featuring five stripes in a center section in yellow, white, and rose gold.
