In 1904, Brazilian aviator Alberto Santos-Dumont complained about the unreliability and impracticality of using a pocket watch while flying. Louis Cartier designed a flat wristwatch with a square bezel, which became the first mass-produced men's wristwatch. Santos-Dumont became the first person to be filmed in an airplane flight in 1906, taking 21.5 seconds with a Cartier watch on his wrist. The Santos-Dumont watch was offered in platinum and yellow gold models. Cartier also developed the deployant mechanism for the straps, which is still used today. The Santos continued to be manufactured through the first half of the 20th century, but its square design declined due to WW2 and military requirements for round watches. In 1978, Cartier redesigned the Santos de Cartier, adding an integrated bracelet and stainless steel case and bracelet, a "bimetal" gold-steel design that became popular in the 1980s.
