1518JRef

Debuting in 1941 as Patek's inaugural Perpetual Calendar Chronograph, the 1518 was a remarkable achievement, housing a hand-wound chronograph with moonphase, day, date, month, and small seconds in a 35mm frame. This legendary model was later replaced by the 2499. The specific piece mentioned, which features an Arabic-numeral dial and dates to 1950, was later sold at a Christie's auction.