Reference 5940 was launched in 2012 and was initially available only in yellow gold. It is distinguished by a thin cushion-shaped case and a dial with Breguet numerals, all features that evoke the vintage era. The Reference 5940 and Reference 5040 are the only two non-round perpetual calendars from the House of Patek and they feature the exact same automatic movement, Cal. 240, as the iconic Ref. 3940 and the Nautilus Ref. 5740G.