Introducing the Audemars Piguet Royal Oak Selfwinding Chronograph 26240ST.OO.1320ST.02. The 41mm case is made of Stainless Steel with a GrandeTapisserie dial in black. Luminescent white gold hand and hour markers work with the Sapphire glare-proofed crystal for optimal legibility in any condition. An exhibition case back gives a glimpse at the "50th Anniversary" oscillating weight. The Calibre 4401 powers all of the watch's complications, including Flyback chronograph timekeeping and date features.