The Patek Philippe reference 5140 was first introduced in 2006, as the latest chapter in a legacy of great perpetual calendars. It is the follow up to the iconic 3940, which is considered to be one of the most important pieces of Patek's modern history, and with which a standard for all modern perpetual calendars was established. With its contemporary 37.2mm size, and svelte profile matched by a slim, micro-rotor movement, it is contemporary, yet refined.