ETA Caliber G15.21A
ETA Caliber G15.21A

ETA Caliber G15.21A

Caliber NumberG15.21A, G1521A
5.25mm thick
32,768 Hz
Battery Cell Number394 (SR936SW)
Battery Life
~36 months (share your experience below)
ETA 258658
Hand Count
Hand Sizes1.50mm / .90mm / .30mm / .20mm x 3
FunctionsCentral hours; central minutes; central central chronograph seconds; small seconds subdial at 6:00; 1/10 chronograph seconds at 2:00; 30 minuts chronograph counter at 10:00; date at 4:00 (various locations available, see below)
Country of ManufactureMade in Thailand (with Swiss parts apparently)
Known Models
Invicta 29985 (Add your watch to the comments below…)

ETA caliber G15.21A is a Swiss parts quartz chronograph movement with 6 jewels.

According to official ETA technical documentation, this movement has been on the market since at least 2003.

As of this post, the ETA caliber G15.21A is no longer listed on the ETA site and has been discontinued. Caliber G15.212 may be a possible replacement.

The metal plate on the movement is signed: ETA (logo) / THAILAND MOVEMENT / SWISS PARTS / SIX 6 JEWELS / Battery 394 9.5 x 3.6 1.55v / G15.21A

Replaceable, Not Repairable:

This movement is part of ETA’s Fashionline group of quartz movements. This movement is largely found in entry level lower priced timepieces. While the G15.21A is not considered to be a repairable movement, it really depends on the issue.

In ETA’s Own Words:

“Movements of these calibres cannot be disassembled; therefore, this document contains information on electrical tests and hand-fitting only.” -ETA official tech sheets

G15.21A Vs G15.211:

The G15.21A and G15.211 both share the same tech sheets – the measurements, jewel count, and functionality are the same. The main difference between these two calibers appears to be the country of origin.

As pictured, the G15.21A is signed “THAILAND MOVEMENT” and “SWISS PARTS”. The G15.211 here is signed “SWISS” with a “V8” stamp as well.

The only other technical difference that was spotted in the drawings of each movement was the central chronograph hand maximum unbalance, which is listed as 0.4 U Nm for the 211 and 0.8 U Nm for the 21A. However, it is also worth noting that the drawings for the 211 were from 2000 and the 21A drawings were dated 2005, so this could just be an minor improvement made to the overall G15 framework.

Note: the information above is just a logical assumption based on various movements I have seen. If you come across a G15.21A stamped with Swiss/V8, then it would disprove this idea. In that case, please post the example in the comments below…

Date Location:

You may see this movement written at G15.21A-4 or G15.21A-D4. The trailing digit refers to the location of the date window. The date can be at 3, 4 or 6, and the position can be tilted or horizontal – all depending on the watch dial design.

This code is mostly used when ordering a replacement movement to make sure the correct datewheel is used to match the calendar aperture on the front of the watch. This digit is not included in the caliber number engraved on the movement itself. Check your dial before ordering a new movement.

How to Change the Battery:

The G15.21A takes battery number 394.

Replacing the battery on your G15.21A watch is very straightforward. The diagram below is from the official ETA tech sheets. As pictured, place your tool between the battery and the arm that holds it in place (#2 in the image below). Gently pry the arm back and the battery should lift up. Try not to bend or break off the arm that holds the battery in place!

Eta G10 71a Battery ChangeTo install the new battery, do the process in reverse, but make sure the battery is placed under the lip first (#3 in the image above). If you install a new battery and the watch doesn’t function properly, it’s possible that the battery is bad. Always try a new battery before giving up.

Eta Caliber G15 211 Battery Slot Ar05

Reset the Chronograph Hand to Zero:

After a battery change, you may need to recalibrate the chronograph hands on your G15.21A powered watchwatch. It’s easy and you don’t need to send your watch back to the company or a watchmaker.

  • Pull the crown to position 2 (date setting)
  • Press the bottom pusher to adjust the central chronograph second hand
  • Press the top pusher to adjust the 1/10 second hand
  • Pull the crown out to position 3 (time setting)
  • Press the top pusher to adjust the 30 minute hand
  • Press the crown in to position 1 (against the case) when finished

*Some manufacturer’s refer to the crown position numbers differently. We always try to refer to the positions the same as the manufacturers do. ETA crown positions are as follows:

Eta Caliber G10 71a Crown Positions

Crown/Stem Removal:

To remove the crown on the G15.21A, look for the stem release hole on the movement near the crown There is a small arrow pointing to it. Putting the crown to date setting position should reveal a button in the hole that you can gently press with your tool to release the stem. Do this carefully and do not press too hard. If you damage the stem release mechanism, there doesn’t seem to be a way to fix it since it’s encased in plastic.

Eta Caliber G10 71a Stem Removal

Metal Plate:

The metal plate on the G15.21A is just a thin cover with sticky adhesive. Below this metal cover you will find an plastic encasing that holds everything together.

Replacement Price:

At the time of this post, replacement prices for the G15.211 were found online in the range of $51.00 – $79.95 USD.

Examples of watches with this movement:

The ETA G15.21A shown on this page was found in this Technomarine Technolady ladies chronograph watch

This watch had a spacer between the battery and the caseback. It’s possible that your watch does not have this setup. Please comment below if you watch has a similar spacer or not.

If your watch does have a spacer and you can’t figure out how to reinstall it after a battery: pay attention to circle on the spacer part and the arrow on the movement – line them up as demonstrated in the image below…

Eta Caliber G15 21a Battery Spacer


  • Relatively inexpensive chronograph functionality with some aspect of “Swiss” labeling.
  • Easy to recalibrate if the chronograph second hand isn’t lining up.
  • Does not need an insulator tab under the battery.
  • It has been around for a while with proven reliability overall.


  • Some may see the “Swiss Parts” and “Thailand Movement” labeling as deceptive.
  • Not serviceable, other than changing the battery.
  • Easy to damage the stem removal mechanism, making it difficult to remove from the case.
  • Poor documentation by the manufacturer.
  • Discontinued by the manufacturer.

Additional Resources:

  • More ETA quartz chronograph movements here
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