Introduction and Launch: The Rolex calibre 720, an early movement introduced by Rolex, is an automatic chronometer designed for the Oyster Perpetual line. It debuted in the early 1940's within the Bubbleback series. Although Rolex never formally endorsed the term "Bubbleback," it is widely recognised to refer to Oyster Perpetual models made from 1933 to 1955. These watches are distinguished by their distinctive, rounded casebacks, crafted to house the thicker automatic movements typical during that era.
