Unquestionably one of Patek Philippe's most recognizable grand complications is the reference 3940; an emblematic perpetual calendar that stands out for its timeless beauty. When it was introduced in 1984, it was the slimmest automatic perpetual calendar wristwatch and replaced the reference 3450.
This example comes from the third series, which ran from 1995 to 2007. Compared to the previous series, one finds a sans serif font style on the subdials. In addition, the hallmarks are now stamped on the back of each of the four lugs rather than the case's side.