The Seiko Presage Sharp Edged Open Heart SPB415 and SPB417 use Seiko’s Caliber 6R5J automatic movement, specified to run for up to 72 hours (three days) when fully wound. An open-heart cutout at 9 o’clock reveals the escapement, while a separate 24-hour subdial sits at 6 o’clock.
What is the 6R5J movement?
Seiko introduced Caliber 6R5J with the SPB415 and SPB417 in an announcement dated April 27, 2023. Seiko specifies an automatic movement with hours, minutes and seconds, a 24-hour indication, a frequency of 21,600 vibrations per hour (six beats per second), and 24 jewels. Its stated power reserve is 72 hours when fully wound. These are manufacturer specifications, not independent test results. Seiko’s April 2023 announcement
The 24-hour subdial is an additional time indication, not a second time zone or a GMT function. The open-heart window at 9 o’clock provides a view of the escapement; it does not change the movement’s stated functions.
SPB415 and SPB417: what differs?
| Specification | SPB415 | SPB417 |
|---|---|---|
| Dial | Shironeri, described by Seiko as unbleached white silk | Aitetsu, described by Seiko as indigo iron |
| Movement | Caliber 6R5J automatic | Caliber 6R5J automatic |
| Stated power reserve | 72 hours when fully wound | 72 hours when fully wound |
| Case and crystal specifications | Same launch specifications for both models | Same launch specifications for both models |
| Launch-market price and availability | April 2023 US launch RRP: $1,200; Seiko said select US retailers would have it from summer 2023 | April 2023 US launch RRP: $1,200; Seiko said select US retailers would have it from summer 2023 |
The price and availability above are historical launch details, not a current quote or stock check. The cited material does not establish current prices or availability. Seiko presents the two references as a pair; the documented differences here are dial color, not movement or stated reserve. Seiko’s launch announcement Seiko’s SPB417 product page
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How the open-heart design fits the Sharp Edged Series
Seiko says the Sharp Edged Series began in 2020 and characterizes it by angular cases, patterned dials, and faceted hands and indexes. On these models, the dial carries an asanoha (hemp-leaf) motif, with the open-heart opening echoing the pattern. Seiko’s announcement says the motif has appeared in Japanese textiles since the Heian period and is traditionally associated with growth and success; that cultural description is Seiko’s account. Seiko’s announcement
The launch specifications include a dual-curved sapphire crystal with anti-reflective coating and a sapphire see-through screw case back. The latter lets the wearer view the movement from the back, complementing the dial-side opening. Seiko also lists a stainless-steel case with super-hard coating and a three-fold clasp with push-button release.
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- OPEN-APERTURE DIAL: this men's automatic watch features a black dial with 24-hour subdial and LumiBrite hands, with a retro watch feel inspired by the 1964 Crown Chronograph
- AUTOMATIC: these self-winding, automatic men's watches are powered by your movement, with a power reserve of 41 hours
- STAINLESS STEEL: features a durable stainless steel watch case, black bezel, and stainless steel watch band
- WATER-RESISTANT: these men's wrist watches are water-resistant down to 50 meters
- 4R39 CALIBER: equipped with the reliable caliber 4R39 automatic movement, this accurate men's watch keeps precise time
Case dimensions and resistance specifications
In its April 2023 US announcement, Seiko listed a 40.2 mm case diameter, 13.5 mm thickness, 10 bar water resistance, and 4,800 A/m magnetic resistance for the watches. These are published specifications, not independently verified performance measurements. Seiko Watch Corporation, April 27, 2023
A regional Seiko Boutique UK listing for the SPB417J1 gives more precise dimensions: 40.16 mm diameter, 13.52 mm thickness, 47.37 mm length, and 20 mm lug width. It also lists 10 bar water resistance and an accuracy range of −15/+25 seconds per day. Those figures belong to that UK regional listing; the accuracy range is a stated specification, not a result from an independent timing test. Seiko Boutique UK SPB417J1 listing
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- OPEN-APERTURE DIAL: this men's automatic watch features a black dial with 24-hour subdial and LumiBrite hands, with a retro watch feel inspired by the 1964 Crown Chronograph
- AUTOMATIC: these self-winding, automatic men's watches are powered by your movement, with a power reserve of 41 hours
- STAINLESS STEEL: features a durable stainless steel watch case, black bezel, and stainless steel watch band
- WATER-RESISTANT: these men's wrist watches are water-resistant down to 50 meters
- 4R39 CALIBER: equipped with the reliable caliber 4R39 automatic movement, this accurate men's watch keeps precise time
What the three-day reserve means in practice
The 72-hour figure is the manufacturer’s stated running time from a full wind. It means the watch can continue running for up to three days without further winding under the specification Seiko publishes; it is not a promise that every watch will run for precisely that duration in every condition. No independent reserve or timing tests are established by the cited sources.
For a wearer rotating watches, a three-day reserve can reduce the chance that the watch stops during a short break from the wrist. If it does stop, it will need to be reset before wearing; the 24-hour subdial is not a second-time-zone display.
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
