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Seiko’s 2024 Prospex Black Series release paired two watches with a shared night-vision-inspired look but very different functions: the automatic SRPK43 is a 200 m diver-style watch, while the solar SSC923 is a Speedtimer chronograph rated to 10 bar. Both use black finishes and green accents, but they are not versions of the same watch.
Why Seiko calls them the Black Series
Seiko describes the series’ black-and-green design as evoking a view through night-vision equipment. Its U.S. product page says, “The all-black design expresses the view seen through a night vision scope.” The SRPK43 uses green LumiBrite Pro against a dark gray dial and black ceramic elapsed-time bezel; the SSC923 carries the same broader visual concept in a Speedtimer chronograph design. Seiko’s U.S. Black Series announcement introduced the concept.
SRPK43 vs. SSC923 at a glance
| Specification | SRPK43 | SSC923 |
|---|---|---|
| Type and task | Prospex automatic diver-style watch | Prospex Speedtimer solar chronograph |
| Movement | Caliber 4R36, automatic with manual winding | Solar caliber V192 |
| Power reserve / operation | Approximately 41 hours of power reserve | Approximately six months when fully charged |
| Water resistance | 200 m (660 ft) | 10 bar |
| Case diameter | 45.0 mm | 41.4 mm |
| Thickness | 13.2 mm on the U.S. release page; 13.22 mm on Seiko’s product page | 13.0 mm |
| Lug-to-lug | 47.7 mm | 45.9 mm |
| Lug width | 22 mm | 21 mm |
| Band or bracelet | Black-coated stainless-steel bracelet | Nylon band |
| Crystal and bezel | Sapphire crystal with magnifier; black ceramic unidirectional rotating elapsed-time bezel | Curved sapphire crystal; ceramic bezel |
These are Seiko’s published specifications, not a substitute for checking fit in person or confirming the details on a current listing. The model specifications appear on Seiko USA’s release page and, for the SRPK43, its official product page.
What kind of watch is the SRPK43?
The SRPK43 is the automatic diver-style model. Seiko lists its 4R36 movement as automatic with manual winding, with approximately 41 hours of power reserve, 24 jewels, a day-and-date display, and a frequency of 21,600 vibrations per hour. Its 45.0 mm case, 47.7 mm lug-to-lug measurement, and 22 mm lug width make it the larger of these two models by the listed dimensions.
#1 Best Overall
- SEIKO WATCH – Seiko SRPL15 Prospex wristwatch.
- COLLECTION – Prospex design.
- CASE DESIGN – Prospex Mare model format.
- MODEL REFERENCE – SRPL15 identifies the specific model.
- WATCH DIAMETER – 41.7 mm.
Seiko says the SRPK43 follows ISO standards for scuba diving and rates it to 200 m (660 ft) water resistance. The black ceramic bezel rotates in one direction to track elapsed time. Consult Seiko’s SRPK43 product specifications for the manufacturer’s full description.
What kind of watch is the SSC923?
The SSC923 is a solar-powered Speedtimer chronograph, not an automatic diver. Its V192 movement is solar powered and Seiko gives an operating duration of approximately six months when fully charged. The listed precision is ±15 seconds per month.
Rank #2
- SEIKO WATCH – Seiko SRPL13 Prospex wristwatch.
- COLLECTION – Prospex design.
- CASE DESIGN – Prospex Mare model format.
- MODEL REFERENCE – SRPL13 identifies the specific model.
- WATCH DIAMETER – 41.7 mm.
Its chronograph measures up to 60 minutes in 1/5-second increments. The dial also includes a 24-hour hand, small seconds, power-reserve indicator, and date display. Water resistance is 10 bar; Seiko’s release does not describe it as an ISO scuba-diving watch.
Which one fits your priorities?
- Choose the SRPK43 if you want an automatic watch with a day-date display, rotating elapsed-time bezel, and Seiko’s stated 200 m water-resistance rating. Its case is 45.0 mm across and it comes on a steel bracelet.
- Choose the SSC923 if you want a solar chronograph with timing functions and a smaller listed case diameter of 41.4 mm. It comes on a nylon band and is rated to 10 bar.
The listed lug widths are 22 mm for the SRPK43 and 21 mm for the SSC923. Those measurements can help narrow a strap search, but confirm the attachment and fit for the specific watch before buying a replacement.
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- WATER-RESISTANT: these water-resistant men's dive watches are ISO scuba-approved to depths of 200 meters
- 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 43.8mm stainless steel watch case and bracelet.
- LUMIBRITE DISPLAY: this men's automatic watch features a highly-legible display with LumiBrite hands and markers
- 4R35 CALIBER: equipped with the reliable caliber 4R35 automatic movement, this accurate men's watch keeps precise time
2024 launch timing and U.S. prices
Seiko USA’s release page projected availability at select U.S. retailers in Spring 2024 and listed launch suggested prices of $765 for the SRPK43 and $750 for the SSC923. These are historical U.S. launch details, not current prices or a statement of present availability. Seiko Watch Corporation’s Japanese announcement, dated January 11, 2024, scheduled the broader four-model Japanese release for February 9, 2024; its market scope and pricing are separate from the U.S. release information. Read the Japanese announcement.
Quick Recap
Rank #4
- KHAKI GREEN DIAL: this rugged sports watch features a khaki green dial patterned to mirror the shape of the bezel’s edge, with Lumibrite dial indicator hands and markers for low light and a magnified day/date calendar
- BLACK BEZEL: this versatile men’s watch features a black ceramic unidirectional bezel with distinctive scalloped edging, for elapsed timing
- AUTOMATIC & MANUAL: SRPE05 automatic watches for men power up with your natural movements, and feature the ability to wind manually, with 41 hours of reserve power
- WATER-RESISTANT: these rugged stainless steel dive watches for men feature a khaki green silicon strap, and are both stylish and robust, following ISO standards for scuba, and are water-resistant to 200 meters
- 4R36 CALIBER: equipped with the reliable 4R36 caliber, these precise men’s wrist watches ensure the most accurate timekeeping
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.
