The 'GMT Master' was first commissioned in the 1950s by pioneering airline Pan Am, and was designed for aviation. An increase in flight distances created demand for a watch that was able to tell the time in two different parts of the world simultaneously, so Rolex built it with an additional hand that could be set to a second time zone. By the 1980s, the watch had developed into the 'GMT Master II' and was already a favourite among collectors. Pre-owned watches have a 24-month warranty from Watchfinder & Co. in conjunction with any remaining manufacturer's warranty. All pre-owned watches are also meticulously inspected by Watchfinder & Co. in house experts and come with a letter of authenticity. For more information, contact one of our experts by emailing firstname.lastname@example.org "