The Audemars Piguet Royal Oak Perpetual Calendar ref. 25820SP brings together two pillars of the manufacture: Gerald Genta's octagonal case and one of the thinnest self-winding perpetual calendar movements ever made. The 39mm case in stainless steel is set with a platinum bezel, a rare and subtle combination. The dial displays day, date, month, leap-year cycle and moon phase, all corrected automatically until 2100. In excellent condition, the 25820SP is a landmark of 1990s haute horlogerie and a highly sought-after vintage Royal Oak complication.
