The first GMT model, Reference 6542, was launched in 1954 and is immediately recognizable by the bright acrylic or “bakelite” bezel insert with the twenty-four hour markings printed on its underside. Next came the now iconic reference 1675, made from 1959 to 1980. Reference 16750 (the present watch) followed in 1981 introducing the quickset feature and a new higher beat caliber 3075 movement. With this update the order of the hands changed from GMT/Hour/Minute/second on reference 1675 to Hour/GMT/Minute/Second on the new model. Much to the delight of collectors, the 16750 retained some of the character of the 1675 with the continued use of an acrylic crystal. Discontinued in 1988, the 16750 is now a highly desirable model.