First released in 1954, the GMT-Master reference 6542 was designed for pilots to use in their line of work. With the rise of international travel in the 1940s and 1950s, Rolex initially created the model for Pan Am airlines to track dual time zones. This ingenious design featured an immediately recognizable bakelite bezel with the twenty-four hour numerals painted on the underside, made to glow in any weather condition. Bakelite was Rolex's material of choice, due to its low reflectivity and high readability. The additional luminous 24 hour tipped hand allowed the viewer to immediately track a second time zone.

Ref Variations : 6542-III59, 6542-6542,