Seiko TMI SII caliber PC21S movement

Hattori SII Caliber PC21S

Seiko TMI SII caliber PC21S movement

Manufacturer Hattori aka Seiko Instruments Inc. (SII)
Caliber Number PC21S
Type Quartz
Size 18.5mm x 3.15mm thick (overall height 4.8mm)
Battery Cell Number SR626SW
Frequency 32,768 hz
Quartz Type Tuning fork type quartz crystal
Stem 354222 / tap 10
Hand Sizes 1.20 / .70 / .17mm
Jewels 0
Functions Hours, minutes, seconds
Country of Manufacture Singapore
Known Models Most cheap quartz watches from China. Add yours to the comments below.

The Seiko Instruments caliber PC21S is a 0 jewels quartz movement found in many ultra-entry level timepieces.


You might find this caliber listed as being produced by Hattori aka Epson aka TMI (Time Module Inc) aka Seiko Instruments Inc. We’re not sure why all the different names, but sure they all lead back to Seiko. Learn more about this here.


The documentation from Time Module states an accuracy of “Less than 30 seconds per month at normal temperature range.”

Replacement Prices

Replacement prices of $7.95 were found online at the time of this post.

Official Documentation

  • Official TMI tech sheets and drawings here

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[…] took the photo sharp enough to zoom in: (still hardly readable) It's a PC21S, made in Singapore, according to this site (first hit in google…don't know how dependable the info is), it leads back to Seiko. […]


And by “Most cheap quartz watches from China” you do mean fake watches right?


Fake only if they try to sell it as something it isn’t. I’ve bought a few that were very open about Made In China, shipped from China. Nothing fake about it, it was a Chinese watch.

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