Cartier Must 21

Cartier Must 21 is a line of steel watches recognisable by its wide bezel: the engraved Roman numerals sit on the bezel, leaving the dial uncluttered. The line's full name is 21 Must de Cartier. It appeared in the last quarter of the 20th century, when Cartier wanted a practical counterpart to its precious-metal models: steel instead of gold, and simple graphics.

Versions differ in metal: the core of the line is stainless steel, with two-tone versions whose central bracelet links are gold-plated, and yellow gold cases. On classic versions the crown is topped with a blue cabochon. In the early 2000s came the sporty Must 21 Chronoscaph chronograph, adding sub-dials, a date under a magnifier and a larger case to the numerals on the bezel.

Within the line, the choice comes down to size, metal and bracelet. One example is the 21 Must Chronoscaph, ref. W10125U2: steel, 38 mm, Cartier 272 quartz calibre, sapphire crystal, black dial with a logo pattern, date at 4 o'clock under a lens, rubber strap with steel links and a folding clasp.

Related Cartier collections include Ballon Bleu and Panthère de Cartier; the Must name is also used in the Cartier Tank collection, which is a separate line.