SEIKO PROSPEX SPB155J1 ALPINIST AUTOMATIC MEN WATCH

Seiko Prospex SPB155J1 — Alpinist Automatic Watch

The Seiko Prospex SPB155J1 Alpinist is a modern expression of one of the most enduring designs in Japanese watchmaking history, presented here in its bracelet format with a see-through caseback — the most formally versatile configuration in the current Alpinist lineup. The 38mm case is the most compact Alpinist currently available at City Chain, and the silver stainless steel bracelet gives it a clean, polished everyday character that the leather strap variants do not share. The green dial preserves the essential Alpinist colourway that has defined the design since 1959, and the see-through caseback reveals the 6R35 calibre at work — a feature that rewards both the technically curious and the collector.

Powered by the in-house 6R35 automatic calibre with hand-winding capability and a 70-hour power reserve, the SPB155J1 delivers reliable everyday performance at +25/-15 seconds per day. The curved sapphire crystal protects the green dial through active daily use. Lumibrite on the hands and hour markers ensures readability at dawn and in low light — the conditions that field and outdoor use most regularly demand. At 38mm and 12.9mm slim, it is the most wearable and most formally appropriate Alpinist in the current lineup.

Key Features

• Seiko 6R35 automatic movement with manual winding — self-winding with the convenience of hand-winding when needed
• Approx. 70-hour power reserve — reliable performance through extended daily use
• Accuracy: +25/-15 seconds per day — dependable automatic timekeeping
• 200M water resistance — robust protection for outdoor and water activities
• Green dial with baton markers — the defining Alpinist colourway since 1959
• Lumibrite on hands and hour markers — superior legibility in low light and pre-dawn conditions
• Curved sapphire crystal — premium scratch resistance and superior optical clarity
• See-through caseback — the 6R35 calibre visible at work
• 38mm silver stainless steel case — the most compact Alpinist format at 12.9mm slim profile
• Screw-down crown — weather-resistant protection for field use
• Date display — everyday practicality built in
• Silver stainless steel bracelet — polished and brushed finish for formal and daily versatility

Why You'll Love It

The SPB155J1 is the Alpinist for those who want the heritage design in a bracelet format — the most versatile and formally wearable expression of the Alpinist story. The 38mm case wears more naturally under a shirt cuff than the 39.5mm SPB121J1, the stainless bracelet transitions from casual to business contexts without a strap change, and the see-through caseback adds an element of horological engagement that the closed-back variants do not share. The 6R35 calibre's 70-hour reserve handles any extended weekend, the green dial preserves the sixty-five year design lineage intact, and the curved sapphire crystal keeps it pristine through daily wear.

SPB155J1 vs SPB121J1 — Bracelet or Leather Strap?

Both models share the same 6R35 calibre and 70-hour power reserve in the Alpinist case. The differences are the bracelet, the case size, and the inner ring. The SPB155J1 has a silver stainless steel bracelet, a 38mm case, a see-through caseback, and no compass inner ring — the more formally versatile and compact choice. The SPB121J1 has a brown leather strap, a 39.5mm case, and an inner compass ring — the more heritage-coded and field-ready choice. Same Alpinist green dial and 6R35 calibre, two completely different wear characters and functional complements.

About the Seiko Alpinist

The Seiko Alpinist was born in 1959 — a watch designed for Japan's mountain climbers at a time when domestic watchmaking was finding its identity in extreme environments. The original Alpinist established the green dial and the compact case proportions that define every Alpinist to this day. Over sixty-five years the design has been refined but never fundamentally altered. The SPB155J1 carries that story forward in its most formally versatile expression.

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. The Alpinist has been part of the Prospex story since before the Prospex name existed — a mountain watch that predates the dive watch, the field watch, and the GPS solar by decades. The SPB155J1 carries that sixty-five year legacy forward in the Alpinist's most formal and everyday-wearable expression.

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

Also available: brown leather strap with compass ring — SPB121J1 and GMT with compass ring — SPB379J1. Explore the full Seiko Prospex Collection or browse all Seiko watches at City Chain Singapore.