Seiko Prospex SPB101J1 Sumo Automatic Diver's Watch - W24151

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Seiko Prospex SPB101J1 Sumo Automatic Diver's Watch - W24151

Name: Seiko Prospex SPB101J1 Sumo Automatic Diver's Watch - W24151
Brand: Seiko
SKU: SPB101J1
Price: 546 GBP
Availability: OutOfStock

Ref. SPB101J1

Among our 158 Seiko watchesThis watch£546

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Stepping up in Seiko's range

The Sumo name has been in circulation among Seiko enthusiasts since the early SBDC references, and the SPB101J1 is its current form — updated with sapphire crystal and revised dial printing, but carrying the same oversized silhouette and the stylised bezel typeface that made the original recognisable. The 6R35 movement is the meaningful upgrade beneath: 70 hours of power reserve means a watch left on the nightstand Friday evening is still running Monday morning. At 45mm the case reads large, but the inward-curving lugs pull the watch down onto the wrist rather than letting it sit proud of it, and the 52.6mm lug-to-lug is less punishing than that number suggests on anything but a very small wrist. The black dial is well-suited to a diver's practical requirements — high contrast, bold hands, and LumiBrite applied generously enough that the watch is genuinely readable in the dark rather than merely luminous. The bracelet clasp includes both a dual push-button release and a fold-out wetsuit extension, which means the watch functions as intended over thick neoprene without improvisation. Link adjustment uses a pin-and-collar system — slower than a tool-free design, but more secure once set, and at 188 grams the bracelet needs to be properly fitted to wear well.

Reference: SPB101J1
Brand: Seiko
Collection: Prospex
Case size: 45mm
Case thickness: 12.9mm
Lug width: 20mm
Case material: Stainless steel
Case shape: Round
Dial: Black
Crystal: Sapphire
Bezel: Rotating
Movement: Automatic
Calibre: 6R35
Functions: Date
Water resistance: 200m
Bracelet / strap: Stainless steel bracelet
Strap colour: Silver
Clasp: Three-fold clasp
Lume: LumiBrite
Retailer: F.Hinds

Additional specifications

Lug-to-lug: 52.6mm
Power reserve: 70 hours

Learn more about Seiko

Kintaro Hattori opened a watch and clock shop in Tokyo in 1881, aged twenty-one, and began manufacturing under the name Seikosha — roughly, house of exquisite workmanship — in 1892. The Seiko name appeared on watches from 1924.

The company's significance is that it broke the Swiss monopoly twice. First on precision: Seiko was appointed official timekeeper of the 1964 Tokyo Olympics and built the quartz chronometers and printing timers to do it, and in the 1960s its movements placed highly at the Neuchâtel and Geneva observatory trials against the best Swiss houses.

Then on technology. On Christmas Day 1969 Seiko released the Astron, the world's first quartz wristwatch, accurate to five seconds a month where mechanical watches managed that per day. The consequences for Switzerland were catastrophic — employment in the Swiss industry fell by roughly two-thirds over the following decade. Seiko deliberately did not enforce its quartz patents, allowing the technology to spread.

The same year it produced the 6139, among the first automatic chronographs, and it has since introduced Kinetic, Spring Drive — a hybrid regulating a mechanical mainspring electronically, giving a perfectly gliding seconds hand — and its own dive and field lines.

Seiko remains fully vertically integrated, making its own hairsprings, quartz crystals, and even the Zaratsu-polished cases, at price points from under a hundred pounds upward.

1881: Kintaro Hattori opens his Tokyo shop.
1924: The first watches carry the Seiko name.
1964: Official timekeeper of the Tokyo Olympics.
1969: The Astron becomes the first quartz wristwatch.
1999: Spring Drive enters production.

All Seiko watches

Also in 7 collections

This watch appears in the Seiko Prospex range (32), Back in Stock (3,734), Stainless Steel Watches (2,581), Automatic Watches (1,570), Sports Watches (707), Watches 44mm and Over (603) and Dive Watches (505).

Temporarily out of stock

F.Hinds is not currently taking orders for this reference. Last listed as available on 5 October 2026. Stock is checked nightly and this page updates when it returns.

Out of stock

What the specifications mean

A mechanical watch built to be worn hard and got wet.

Strengths

200m water resistance, rated for actual diving
52.6mm lug-to-lug keeps the 45mm case wearable
Sapphire crystal, which resists scratching
70-hour reserve survives a weekend off the wrist
Luminous hands and markers for low light

Worth knowing

45mm is a large watch with real presence

Best forDivingSwimmingEveryday wear

Less suited toSmall wrists

Seiko Prospex SPB101J1 Sumo alternatives

Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.

Prospex SPB101J1 Sumo Automatic Diver's Watch - W24151 compared with 2 alternatives from other brands
Specification	This watchProspex SPB101J1 Sumo Automatic Diver's Watch - W24151SPB101J1	CasioG-SHOCK GM-B2100BD-1AER Solar Bluetooth Black IP Bracelet Watch - W17649GM-B2100BD-1AER	BulovaMarine Star 98A302 Automatic Bracelet Watch - W0931198A302
Price	£546	£549	£469
Case size	45mm	44mm	45mm
Water resistance	200m	200m	200m
Movement	Automatic	Automatic	Automatic
Strap	Stainless steel bracelet	Stainless steel bracelet	Stainless steel bracelet
Power reserve	70 hours	—	42 hours
	This watch	Closely matched	Costs less