Monochrome Watches
An online magazine dedicated to fine watches

The Seiko 5 Sports “Time Sonar” SRPJ45 and SRPJ47

The appeal of translucent dials coupled with aggressively competitive prices.

| By Santiago Tejedor | 3 min read |
Seiko 5 Sports Time Sonar SRPJ45K1 SRPJ47K1

It’s fair to say that the Seiko 5 Sports collection is one of the most versatile mechanical watch lineups in its price range. If on top of versatility, we tally the factor of manufacture-made movements, as well as the overall quality the Japanese brand is known for, the Seiko 5 Sports collection is practically unbeatable. A potential contender could be the Swatch Sistem51 – with even lower prices – but without the range and resilience of a Seiko 5 Sports model. And some new “Time Sonar” models have recently been released… Sounds familiar? Yes, but these new references SRPJ45 and SRPJ47 are a bit different and non-limited.

Seiko 5 Sports Time Sonar SRPJ45K1 SRPJ47K1

In addition to the traditional configuration and Field models, we’ve seen the Seiko 5 Sports watch emblazoned with the motorcycle livery of the Honda Super Cub. It has also been reinterpreted by Japanese artist Kosuke Kawamura with cool, colourful translucent dials inspired by the 1970s Time Sonar-inspired references SRPJ41 and SRPJ43. The success of the Time Sonar was so swift that I never got to see a model in the metal. Luckily, the translucent dial concept is back in a non-limited edition.

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Seiko 5 Sports Time Sonar Blue SRPJ45 SRPJ45K1

I have to admit that when I first looked at the SRPJ45 and SRPJ47 on Seiko’s website, my reaction was, “this is a mistake.” However, as we all know, seeing the watch in the metal is a very different experience, and my impression changed radically.

Externally, both references share specs with other Seiko 5 Sports models: robust steel cases, 42.5mm diameter with 13.40mm height and anodised aluminium bezel inserts surrounding the proprietary flat Hardlex mineral glass. Naturally, the crown at 4 o’clock retains its position. While it isn’t a screw-down crown, it is protected by two crown guards, making it very difficult to pull out accidentally. Although the absence of a screw-down crown and the lack of a luminous dot on the bezel mean it is not a professional dive watch, the markings on the bezel and the 100m water-resistance ensure it can handle a lot more than an accidental splash.

Seiko 5 Sports Time Sonar SRPJ45K1 SRPJ47K1

The coloured part of the two-tone bezels – a slightly Tiffany-like shade of blue on the SRPJ45 and a dark, slightly burnt orange on the SRPJ47 – is echoed on the tinted mineral glass that reveals the date and date discs. The circular or snailed engraving on the glass produces a slightly blurry, frosted effect that comes into full focus when the day and date appear in the elongated rectangular aperture at 3 o’clock with a crisp white background.

Sharing the same style of hands and hour markers as other Seiko 5 Sports models, the central seconds hands have a coat of yellow (SRPJ47) or orange paint (SRPJ45), depending on the model. Of course, Seiko’s proprietary LumiBrite treatment is superlative.

Seiko 5 Sports Time Sonar Orange SRPJ47 SRPJ47K1

The reverse side of the watch reveals a darker tinted glass that shows Seiko’s entry-level but indestructible in-house 4R36 automatic calibre with 3Hz frequency, 42h power reserve, stop seconds and manual winding.

Seiko 5 Sports Time Sonar Orange SRPJ47 SRPJ47K1

As I mentioned at the beginning of this article, the pricing of Seiko 5 Sports watches is hard to beat. Retailing for EUR 310, the two references – SRPJ45 (blue) and SRPJ45 (orange) – come with a 2-year guarantee and can be bought online at, at Seiko boutiques and at authorised retailers.

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