The new Patek Philippe's ref. 5320G is a new perpetual calendar that has been inspired by many predecessor models that attracted global attention in the 1940s and 1950s. In 1925, Patek Philippe launched model 97'975, the world's first wristwatch with a perpetual calendar. It was followed by further unique pieces. Eventually, the manufacture integrated this type of watch in its regular collection with the ref. 1518 perpetual calendar chronograph released in 1941. A year later, Patek Philippe introduced the ref. 1526 Perpetual Calendar without a chronograph.