The reference 5270 perpetual calendar chronograph was introduced in 2011 (the pink gold version was introduced in 2015) and it featured for the first time an inhouse Patek Philippe chronograph movement (for the 3970 and 5970 Patek Philippe used a heavily modified Lemania base). It also added a day/night and leap year indicator on either side of the moonphase/date indication.

Ref Variations: 5270R-001,5270G-001,5270G-014,5270G,5270G-013,5270P-001,5270G-018,5270g-015,5270-1R-001,5270G,5270R,5270P,