The Patek Philippe reference 5146 is one of the brand's most celebrated Annual Calendar models, combining timeless Calatrava-inspired design with exceptional everyday functionality. Introduced in 2005, it features Patek Philippe's renowned Annual Calendar complication, automatically distinguishing between 30 and 31-day months and requiring adjustment only once each year at the end of February. The beautifully balanced dial displays the day, date and month through three apertures, complemented by a moon phase, 24-hour indicator and power reserve display. Powered by the automatic Calibre 324 S IRM QA LU, the 5146 exemplifies Patek Philippe's outstanding craftsmanship, refined finishing and mechanical excellence. Produced in a variety of precious metal configurations, the reference has become a modern classic, admired for its elegant proportions, practical complication and enduring appeal among collectors.