Launched in 1955, the GMT-Master witnessed the rapid expansion of intercontinental travel in the latter half of the 20th century. It even became the official watch of Pan American World Airways, the most prominent American international airline at the time. The GMT-Master, a true “tool watch”, evolved continually, to offer increasing technical performance. In 1982, Rolex introduced a new movement that allowed the hour hand to be set independently of the other hands. To clearly mark this evolution, the model fitted with the optimized movement was named the GMT-Master II.