Patek Philippe, Calatrava Officer, Ref. 5053 in Pink Gold. The design of the general's case back originated from the hinged case back of pocket watches in the war years and was later transplanted to watches. In 1989, Patek Philippe launched a series of limited-edition watches to celebrate the brand's 150th anniversary. Among them, the hour and minute display watch Ref.3960 with a master's case back was widely popular and is also believed to have driven the return of the master's case back design in modern watches. Subsequently, Patek Philippe launched a series of official case back watches, one of which was the Ref.5053. Ref.5053 was briefly produced from 2001 to 2005 and features a series of classic elements: straight lugs, lugs fixed with screws, and those connected to the case through a hinge structure