Seiko Upgrades the “62MAS” Prospex Diver

A new calibre in compact case rated to 300 m.

A bestseller available in several variants to date, the modern-day “62MAS” now gets a substantive upgrade with the Prospex 1965 Heritage Diver’s Watch. The new diver is a direct successor of cal. 6R35-powered models, including the SPB143 and SPB239 of 2021.

Released in two regular-production models (SPB451 and SPB453), plus a 100th anniversary special edition (SPB455), the latest Prospex “62MAS” improves on earlier models in three key areas: water resistance is now 300 m, the case is slightly more compact, and the movement is now the cal. 6R55 with a 72-hour power reserve.


Initial Thoughts

As is usually the case with Prospex dive watches, the latest take on the 62MAS is robust and good looking. The new divers are safe bets as they rely on a proven formula – the classic 62MAS design with improved technical features. The SPB455 in particular stands out with its vintage-flavoured gilt accents.

That said, the designs stay traditional; these are difficult to distinguish from their predecessors at a distance. A more distinctive design, perhaps with patterned dials that Seiko excels in, would have made these more compelling.


Importantly, the new trio also stays in the sub-US$1,500 price segment. Few dive watches in this price range have the same historical provenance, since Seiko was a pioneer in dive watch development.

The regular production pair are only US$100 pricier than the SPB143 (and the special edition an extra US$200). The premium is easily justified given upgrades including the next-generation cal. 6R55 and 300 m of water resistance.

Though Seiko’s average pricing has crept up over the years, it has been accompanied by steady improvements in features and finish. At US$1,300 for the standard model and US$1,400 for the special edition, the new models remain an excellent value proposition.

New movement, new case

Despite the visual similarities between the new diver and past models, the latest “62MAS” is a different watch. To start with, it has a more compact case that’s 40 mm in diameter, 13 mm high, and 46.4 mm in lug-to-lug length. In comparison, its predecessor is 40.5 mm by 13.2 mm by 47.6 mm.

The biggest change in dimensions lies in the lug-t0-lug length, which is over 1 mm less thanks to shorter lugs that were designed for better wearability. Notably, Seiko also redesigned the bracelet for the same reason. The bracelet now features shorter links and a small folding clasp so it fits better on a wider range of wrists.

Besides its size, the case also gains greater water resistance. It’s now rated to 300 m, as opposed to 200 m for past models. According to Seiko, the new diver has the greatest depth rating of any non-saturation-diving watch in its catalogue.

The movement inside has also been improved with the installation of the cal. 6R55. An evolution of the cal. 6R35 found in past “62MAS” models, the cal. 6R55 is the latest generation self-winding movement intended for Seiko’s mid-range watches.

SPB455 special edition

Used here for the first time in a Prospex model, cal. 6R55 has a slight increase in power reserve to 72 hours, along with a reduced overall height, contributing to the thinner case.

In terms of design, the three new models stick closely to the historical “62MAS” look, retaining the oversized hour markers and baton hands. However, the dial design has been gently tweaked, most notably with the date window now located between four and five, rather than at three as before.

All three models share the same specs, differing only in dial colours. The regular product models have either a radially-brushed blue or matte-black dial, matched with white luminous paint on the dial and hands.

From left: SPB451, SPB453, and SPB455

The 100th anniversary special edition, on the other hand, has a sunburst grey dial with faux-vintage luminous paint. This is matched with gilt hands and markings on the bezel.

Additionally, the special edition is delivered with a fabric strap in addition to the bracelet. The NATO-style strap is woven from recycled plastic bottles using a traditional method known as Seichu. According to Seiko, the strap is four times stronger than conventional fabric straps, as well as resistant to degradation from exposure to sunlight.

The SPB455 on the fabric strap

Key facts and price

Seiko Prospex 1965 Heritage Diver’s Watch
Ref. SPB451
Ref. SPB453
Ref. SPB455 (100th anniversary special edition)

Diameter: 40 mm
Height: 13 mm
Material: Stainless Steel
Crystal: Sapphire
Water resistance: 300 m

Movement: Cal. 6R55
Functions: Hours, minutes, and seconds
Winding: Automatic
Frequency: 21,600 vibrations per hour (3 Hz)
Power reserve: 72 hours

Strap: Matching bracelet; SPB455 includes additional fabric strap

Limited edition: No
Availability: Starting June 2024
Price: US$1,300 (SPB451, SPB453), US$1,400 (SPB455)

For more information, visit

This was brought to you in partnership with Seiko.

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