Eterna Caliber 520u

Eterna Caliber 520U

Eterna Caliber 520u

Caliber Number520U
Base Caliber
Eterna 520
Movement TypeManual wind, mechanical
Diameter12”’ (26.5mm)
Lift Angle42 degrees (needs confirmed)
Power Reserve42 hours
Vibrations Per Hour18,000 bph
Balance StaffU620
Hands1.38mm / 0.80mm / 0.13mm
Anti-ShockEterna-U Device
FeaturesHours, minutes, small seconds
Country of ManufactureSwitzerland
Production Years1940s – 1950s
Known Models1952 Eterna dress watch

The Eterna caliber 520U is a vintage mechanical movement based on the Eterna caliber 520. These calibers were produced in the 1940s and 1950s.


The 520U movement seen here is equipped with an in-house anti-shock device called Eterna-U.

Other Variations

There are a few variations of the 520 movement with a letter designation based on the type of anti-shock device used. The ones we know about are:

  • 520 – the base caliber (4mm height)
  • 520H – Eterna-H shock absorber
  • 520L – Eterna-L shock absorber
  • 520S – central sweeping seconds (4.95mm height)
  • 500U – shown here

If you know more about these variations of the caliber 520, or know of some not listed, please leave the information in the comments.

The movement pictured above was found in a vintage Eterna dress watch here.

About Eterna

Eterna was founded in 1856 in Grenchen, a municipality of Solothurn, Switzerland. Despite many people thinking that Eterna is part of the Swatch Group, the watch brand is owned by a Hong Kong watch conglomerate known as Citychamp Watch & Jewelry Group. ETA, the movement branch of Eterna that was established in 1932, became part of the Swatch Group and still produce movements that we know today. Eterna also still produces movements and modules for modern timepieces.

Please share your experiences and thoughts about the Eterna caliber 520U in the comments section below…

Caliber submitted by

Caliber Corner is the world's most popular resource for watch movement pics, specs, mods and DIY repairs. Be sure to check out the member's forum and follow @calibercorner on Twitter, Instagram and YouTube (NOT Facebook). Join our mission to spread movement awareness! Login/Sign-up

Community Reviews & Questions:

  • Keep comments respectful and follow our community guidelines.
  • Keep comments on the topic of Eterna Caliber 520U

For off topic or general watch questions, post in the Caliber Corner Forum.


newest most voted
Inline Feedbacks
View all comments
Service: Eterna Dress Watch with In-house 520U Movement - WahaWatches
5 years ago

[…] movement is the Eterna 520U with 15 jewels and a hidden ratchet wheel and crown wheel. It’s Eterna’s first caliber […]

What Watch to Wear to a Job Interview - WahaWatches
4 years ago

[…] presumably the most versatile watch that I own. A 1952 Eterna ref. 106BDT, with Eterna’s in-house calibre 520U inside. It’s understated, but neither not enough nor too much. Just a simple watch in excellent […]

Seagull Caliber St19

Join our mission to spread movement awareness!

Members Online

  • admin Zachmonoda

Recent Forum Posts

Trending Comments


ALTO Caliber A01

One of the coolest looking movements I've seen in a long time!


Miyota Caliber 2115

Found in the Aviator branded Special OPS AVW78341G350. It ticks along with +2 sec./month, thats…


ALTO Caliber A01

What's with these prices. It's 20k and has the same regulating system in my $500…


Sunon Caliber PE11

Sunon is a part of GUANGZHOU Pearl Time Group, PE11 is the only repairable movement…


ETA Caliber 2824-2

Hi Craig, that would be the hour wheel. Tech sheets were added to the caliber…


Would love your thoughts, please comment.x