The Patek Philippe reference 5905 is one of the manufacture's most accomplished contemporary complications, combining an Annual Calendar with a flyback chronograph in a refined and highly wearable design. Introduced in 2015 as the successor to the reference 5960, the 5905 is powered by the automatic in-house Calibre CH 28-520 QA 24H, featuring a column wheel, vertical clutch and flyback chronograph alongside Patek Philippe's patented Annual Calendar, which requires correction only once each year at the end of February. Its clean, highly legible dial displays the day, date and month through apertures across the top of the dial, complemented by a 60-minute chronograph monocounter at 6 o'clock and central chronograph seconds, creating one of the manufacture's most balanced and practical complication layouts. Produced in white gold, rose gold and later platinum, with a variety of dial colours throughout its production, the 5905 has become one of Patek Philippe's most sought-after modern references, admired for its elegant proportions, technical innovation and seamless integration of two of the manufacture's most celebrated complications.