Audemars Piguet

Introduction The Audemars Piguet Royal Oak 5402 “Jumbo” is one of the most iconic watches in modern horology, but its early production history has long been misunderstood. This article consolidates findings from WatchProSite contributors and AP archival s...  

Thanks for sharing all of this information, and linking the other posts. I am a novice on the 5402.

It is steel and gold two-tone. But I don't think it's a Jumbo size. How would I know if it's a 5402? do I have to read all those linked files to find out or will someone just shout at me "You dope, that's a XXXX not a 5402" Ignorant of the ways of AP Mike...  

The 4100SA indicates Steel & Gold (“SA”=acier/acier‑or) version of that reference. It is noted as having a non‑screw‑down crown, which means its water‑resistance is more limited. Typical dial signature: at the 6 o’clock position it says “Swiss” only (at l...