As commercial airlines expanded their services globally, Pan American Airlines sent Rolex a request for a watch to keep track of multiple time zones simultaneously. In 1954 Rolex presented their first GMT (“Greenwich Mean Time”) Master model (6542), which included a new movement (1036) and an extra 24-hour hand. The GMT-Master II allows any traveler to keep track of 3 time zones simultaneously. Models compatible with Everest straps are the GMT Master 16700 series and all GMT-Master II non-ceramic models.