Introduced in 1986, the Patek Philippe reference 3970 succeeded the legendary ref. 2499 as the house’s perpetual calendar chronograph. It was the first in the family to indicate leap years and the first to add a 24-hour chronograph hand, and its case was reduced to 36 mm from the 37.5 mm of its predecessor. This third-series example in 18k yellow gold runs the manual-wind CH 27-70 Q, a movement developed from a Lemania calibre base. The reference remained in production until 2004.
