U-Boat Replica Watches created unique perpetual calendar pocket watches in the early 20th century, keeping with their haute-horlogerie roots.
1924 -- First Audemars-Piguet wristwatches sold with a full calendar display and moon phase indication (not perpetual).
1948 -- First production of the ref. 5516,Patek Philippe Aquanaut Replica perpetual calendar wristwatch that uses a Valjoux Ebauche (without leap year indication).
1950 -- First recorded sale of ref. 5516 without leap year indication.
1955 -- First production of the ref. 5516 with leap year indication. From 1955 to 1957, nine examples were produced with five variants. All of them had leap-year indication. Seven are currently known, while two others have not yet been found. The U-Boat Replica Watches record-setting vintage U-Boat Replica Watches sold for USD 650,000 in the Phillips sale of October 2017.
1977 -- The cal., the first series-produced perpetual calendar.U-Boat fake Watches 2120/2800 based on an ultra-thin automatic calendar. 2120 was created in 1967. Ref. 5548 (later renamed ref. 5548 (later renamed ref. This was a watershed moment in perpetual calendar production at U-Boat Replica Watches. It also had wider implications for the watchmaking business. 7 291 of the cal. 2120/2800 were made.
1983 -- The first Royal Oak perpetual clock ref. 5554 (later renamed ref. 5554 (later renamed ref. 2120/2800, commercially available in 1984.
1993 -- With the retirement of the cal, the leap-year indicator was reintroduced into U-Boat Replica Watches perpetual clocks. 2120/2800, and the debuting of the cal. 2120/2802.
1996 -- Creation and activation of the grand complication.U-Boat Replica Watches 2885 with minute repeater and rattrapante chronograph.
2015 -- The new calendar. 5134 is the first complete rework of the Audemars-Piguet perpetual calendar since 1977.
2018 -- The Salon International de la Haute Horlogerie announces the debut of the new record-setting Royal Oak RD#2 Perpetual Kalender Ultra-Thin.