The Seiko Speedtimer wristwatch has been produced since 1969. It was the world’s first automatic chronograph with caliber 6139. The new generation of watches from the Japanese brand is represented by three models. They differ in design. You can purchase the new models at official Seiko stores or from authorized dealers.
What is Seiko with caliber 6139 like?
For those unaware, the caliber provides watchmakers with information about the mechanism, features, manufacturer, and functionality of the watch. Essentially, the caliber is a code. The highlight of Seiko watches is their high complexity. Not every watchmaker can understand how wristwatches work. Accordingly, a master must be knowledgeable in repair and maintenance. Training is conducted through understanding these very calibers.
Calibers have digital markings and can be classified by their operating principle:
- Analog quartz – quartz calibers with analog hands on the dial.
- Digital quartz – quartz watches with an electronic dial.
- Handwind – mechanical chronometers that need to be wound manually.
- Automatic – automatic mechanism that does not require manual winding.
We can also recall about jewels. Many have heard the phrase “number of jewels in a watch.” Jewels refer to rubies (crystals). They are used in moving mechanisms. The number of jewels in a watch depends on the complexity of the mechanism and functionality. In the 21st century, jewels have been replaced with synthetic materials. However, some brands still incorporate rubies into their mechanisms.
Solar chronographs Seiko Prospex Speedtimer
The feature of the new models is reliability and flawless operation. The watch design is well thought out. The large dial is highly informative and will be interesting even for people with vision problems. The second hand is enlarged, reaching the tachymeter on the edge of the dial. The chronograph minute hand is red. The date window is enlarged and easy to read.
All three models are equipped with a 60-minute chronograph and a 24-hour additional dial. They feature a built-in solar battery and energy reserve. When fully charged and without light, the watch can operate for up to 6 months.
The minute and hour hands, as well as 12 indices, are coated with Lumibrite. The light storage is convenient for information visibility in low light or darkness. The second markers are on the inner ring of the bezel and are clearly visible from different angles.
The sapphire glass is curved, scratch and chip resistant. Its unique shape combines both classic and sporty styles, which is rare for wristwatches. The dial has an anti-reflective coating. Even in bright sunlight, readability remains high. Overall, the implementation is similar to all Seiko Prospex series watches.
Seiko Prospex Speedtimer: SSC911, SSC913, SSC915 – Technical Specifications
| Watch type | Mechanical, automatic winding, 24-hour hand, solar chronograph, solar-powered |
| Power reserve indicator | Present |
| Case material | Stainless steel |
| Bracelet material | Stainless steel |
| Glass | Sapphire, with anti-reflective coating |
| Water resistance | 10 ATM |
| Magnetic resistance | 4800 A/m |
| Case diameter | 41.4 mm |
| Case thickness | 13 mm |
| Control | Three mechanical buttons |
| Price | Approximately 700 Euros (for Europe) |
Compared to smartwatches and fitness bands, the wrist chronographs of the Japanese brand have more prospects. They are a classic that cannot be replaced. Seiko wristwatches are designed for decades of daily use. They offer precision, reliability, and status. If you’re choosing between “smartwatches or mechanical classics” – weigh everything and make the right choice.
Source: seikowatches.com





