MichaelC[AP Moderator]
22251
Welcome here, Pete.
Looks like you have gained an answer to your question directly from Audemars Piguet!
Some insights
By: Audemars Piguet : July 14th, 2015-05:41
The first Royal Oak was launched in 1972 as Ref. 5402, fitted with calibre 2121 and housed in a 39 mm case . Ref. 14790 / calibre 2125 / 36 mm case / ninenties. Ref. 15202 / calibre 2121 / 39 mm case / around 2000. Ref. 15300 / calibre 3120 / 39 mm case /...