The Royal Oak Chronograph was a latecomer to this celebrated line and has remained remarkably consistent throughout its two-decade life. All share the same movement and a single lineage passes from the original Ref. 25860 to the subtly-redesigned Ref. 26300, the up-sized Ref. 26320, and the new Ref. 26331. It was only this year that a second model, the 38 mm Ref. 26315, was added. Yet on closer examination, a world of differences emerges, from the City of Sails to the Leo Messi, to the new 41 mm dial. Through it all, the Royal Oak Chronograph remains one of the classiest and most comfortable watches available.