Calibre 552 — the uncertified 551, engine of the Railmaster

In brief

Twenty-four jewels, exactly as on the 551 — but Omega never sent this one for chronometer testing. It went into the Railmaster, among other watches.

Short history

Omega slotted it into the 1959 no-date line-up. The architecture is the 551's, 24 jewels and all, but the movement never went through official chronometer certification, which made it a little cheaper to build.

Watches that used it

• Railmaster
• Seamaster automatic