The Audemars Piguet Royal Oak Perpetual Calendar reference 26574OR.OO.1220OR.01 was introduced in 2015. At 41mm, its case is slightly larger than its predecessors. Accordingly, the self-winding caliber 5134 is slightly larger as well - plus a week number indicator has been added. In this configuration, case and bracelet are pink gold; the 'Grande Tapisserie' dial is blue.