1518ARef

Debuting in 1941, the 1518 was Patek's inaugural Perpetual Calendar Chronograph, packing a hand-wound movement with moonphase, date, and chronograph functions into a 35mm case. Of the 281 pieces produced, only four were made in stainless steel, with one achieving a record-breaking CHF 11,002,000 at a 2016 Phillips auction. Note that the provided price graph is for illustrative purposes only.