The original Rolex GMT-Master was first made in partnership with Pan American Airways, enabling its staff to keep track of Greenwich Mean Time. Airline staff needed to know GMT in order to fill out paperwork and plan aviation schedules. The original GMT-Master has a 24-hour bezel with a fourth-hand that revolves once per day. The idea was that the fourth hand would be set to GMT time, allowing its owner to read two time zones at once. This inventive addition made the GMT-Master an immediate hit amongst globetrotters, who admired its functionality, robustness and versatile appearance. For those who travel, or enjoy a watch with tasteful specialist features, the pre-owned Rolex GMT-Master is a great choice.