Without much of an introduction needed, the Audemars Piguet Royal Oak has become one of the most iconic, important and sought-after timepieces in recent times. With an ever-growing cult-like following, the Royal Oak family has offered a wide array of important timepieces throughout its entire lineage, one of which is the Royal Oak chronograph. Making its debut in 1998, early examples featured a 39mm diameter case via the ref. 25860ST.