Seiko Prospex SPB103J1 — Sumo Automatic Diver's Watch

The Seiko Prospex SPB103J1 is a green dial Sumo diver — the Sumo case shape paired with one of the most distinctive and ocean-connected dial colours in the Prospex lineup. The Sumo is known for its wide 45mm case that distributes its diameter across the wrist with exceptional comfort, and the green dial gives the SPB103J1 a vivid, collector-coded character that stands apart from the darker and more common blue and black variants in the broader Seiko diver family. Powered by the in-house 6R35 automatic calibre with hand-winding capability and a 70-hour power reserve, it delivers a professional diver's specification — Diver's 200M water resistance, unidirectional rotating bezel, and screw-down crown — with one of Seiko's most capable mid-range automatic movements.

The sapphire crystal protects the green dial through active daily use, and Lumibrite on the hands and hour markers ensures readability at depth and in low light. At 45mm and 12.9mm slim, the Sumo case wears with comfortable, substantial wrist presence — the cushion-like proportions sit closer to the wrist and distribute the case weight naturally, making it one of the most comfortable 45mm divers available. The silver stainless steel bracelet completes a classic, versatile presentation.

Key Features

• Seiko 6R35 automatic movement with manual winding — self-winding with the convenience of hand-winding when needed
• Approx. 70-hour power reserve — dependable performance through an extended weekend without wearing
• Accuracy: +25/-15 seconds per day (5°C–35°C) — dependable automatic timekeeping
• Diver's 200M water resistance — built for recreational diving and water sports
• Green dial with baton markers — vivid, ocean-connected, collector-coded colourway
• Lumibrite on hands and hour markers — superior legibility in low light and underwater conditions
• Unidirectional rotating bezel — purpose-built for safe and accurate dive timing
• Sapphire crystal — premium scratch resistance and superior optical clarity
• 45mm silver stainless steel case — Sumo proportions at 12.9mm slim profile
• Screw-down crown — water integrity protection for diving use
• Date display — everyday practicality built in
• Silver stainless steel bracelet — durable, comfortable, and corrosion-resistant

Why You'll Love It

The SPB103J1 is the Seiko Prospex Sumo for those who want the green dial — and among Sumo variants, green has a specific resonance with collectors and ocean enthusiasts that blue and black do not share in the same way. The Sumo case shape is celebrated for its comfort at 45mm: the broad, slightly cushioned proportions distribute the case width across more wrist surface area than a standard round case, making it significantly more comfortable than its dimensions suggest. The 6R35 calibre's 70-hour reserve handles any extended weekend, the sapphire crystal protects the green dial, and the Diver's 200M rating means it is ready for the water. A green Sumo diver that earns its collector status through both the case and the colour.

The Seiko Prospex Story

Prospex is a combination of the words "Professional" and "Specifications." Seiko Prospex timepieces are designed to be practical, reliable, and durable — built to meet the high standards required in extreme environments for sports lovers and adventure seekers alike. The story begins in 1881, when Kintaro Hattori founded a clock and watch shop in Ginza, Tokyo — the business that would become the Seiko of today. Since 1965, when Seiko created Japan's first diver's watch, the Prospex dive line has stood for underwater precision and reliability. The SPB103J1 carries that sixty-year legacy forward in one of the most distinctive green dial expressions in the Sumo family.

Backed by Seiko's official warranty. Authentic Seiko Prospex watch, sold by authorised retailer City Chain Singapore.

Explore the full Seiko Prospex Collection or browse all Seiko watches at City Chain Singapore.