Seiko Prospex Sumo SPB343J1 Taiwan Limited Edition Automatic Diver

The Seiko Prospex Sumo SPB343J1 is a Taiwan-exclusive Prospex diver built on the classic Sumo silhouette. Seiko nicknamed the theme for watching sunrise on Taiwan’s eastern coast: a gradient blue dial that lightens toward the centre, paired with a black stainless-steel case and a warm orange accent on the unidirectional bezel from 12 to about 4 o’clock. Under the dial sits Seiko’s Caliber 6R35 automatic — 24 jewels, roughly 70 hours of power reserve, hacking seconds and hand-winding.

At 45mm across with a substantial presence on the wrist, the Sumo case remains a true tool-watch shape: screw-down crown, screw case back marked Limited Edition, sapphire crystal with inner anti-glare treatment, and 200m water resistance. LumiBrite on the hands, indices and bezel keeps the dive layout readable in low light. You get a stainless-steel bracelet plus an extra blue silicone strap for a softer, shore-ready option.

Why you’ll love the SPB343J1

• Distinct limited dial — gradient ocean-blue face with a sunrise orange bezel segment that stands apart from standard black or sunburst Sumos.
• Proven Prospex diver platform — unidirectional timing bezel, date window, screw-down crown and 200m WR for swimming, snorkelling and wet-weather daily wear.
• Caliber 6R35 — automatic with manual wind, ~70-hour reserve and day-to-day accuracy rated +25 to −15 seconds per day.
• Sapphire crystal — hard, clear glass with anti-reflective coating on the inner surface.
• Two straps in the package — steel bracelet for a solid tool look, plus a silicone strap when you want lighter wear.
• Collector-scale run — Taiwan market limited edition of 500 pieces with Limited Edition case-back marking.

Who it suits

Pick the SPB343J1 if you want a full-size Seiko Prospex Sumo automatic with a story-led limited dial rather than a plain catalogue colourway. It suits collectors who already like the Sumo proportions, divers who prefer sapphire and a longer power reserve than entry 4R movements, and buyers looking for a less common Prospex reference in Australia. If you need something under 42mm or a softer dress profile, look at Seiko Presage or smaller 5 Sports models instead.

Technical specifications

• Reference: SPB343J1 (SPB343)
• Collection: Seiko Prospex Sumo — Taiwan Limited Edition (“Sunrise of the Eastern Coast”)
• Movement: Seiko Caliber 6R35 automatic, 24 jewels, manual winding, hacking seconds
• Power reserve: Approximately 70 hours
• Accuracy: +25 to −15 seconds per day (manufacturer rating)
• Case: Black-finish stainless steel, about 45mm diameter
• Crystal: Sapphire with anti-glare coating on the inner surface
• Bezel: Unidirectional rotating dive bezel with LumiBrite accent
• Dial: Gradient blue with LumiBrite hands and hour markers; date display
• Water resistance: 200 metres (20 bar)
• Crown / case back: Screw-down crown; screw case back with Limited Edition marking
• Bracelet / strap: Stainless-steel bracelet; additional silicone rubber strap (lug width typically 20mm on Sumo)
• Limitation: 500 pieces (Taiwan exclusive release)

Frequently asked questions

What is the water resistance of the Seiko SPB343J1?

The SPB343J1 is rated to 200 metres (20 bar). That is proper dive-watch territory for swimming, snorkelling and surface water sports. Rinse the watch in fresh water after salt exposure and service gaskets on a normal diver schedule if you swim often.

What movement does the SPB343J1 use?

It uses Seiko’s Caliber 6R35 automatic: 24 jewels, roughly 70 hours of power reserve, hand-winding and a hacking seconds hand so you can set the time precisely. Rated accuracy is +25 to −15 seconds per day.

Is the SPB343J1 suitable for everyday wear?

Yes, if you are comfortable with a bold ~45mm tool case. The black finish and blue dial work with casual and smart-casual outfits; many owners treat Sumos as daily watches. The 70-hour reserve also helps if you rotate watches over a weekend.

How does the SPB343J1 compare to a standard Seiko Sumo?

Core Sumo geometry and Prospex diver features are familiar: large case, 200m WR, unidirectional bezel and a modern 6R-family automatic. The SPB343J1 stands out with its Taiwan-only sunrise gradient dial, orange bezel accent, black case treatment, sapphire crystal and a small 500-piece limited run rather than an open catalogue colourway.

Where can I buy the Seiko SPB343J1 in Australia?

Chronospride stocks authentic SPB343J1 pieces for Australian delivery. We inspect watches before dispatch. Free shipping Australia-wide on eligible orders.

Authentic stock, inspected before dispatch. Free shipping Australia-wide on eligible orders. Covered by Chronospride’s 12 months warranty, handled by our team. See our authenticity and warranty page.