Seiko make a microbrand move by tweaking the 20MAS

Seiko make a microbrand move by tweaking the 20MAS

Buffy Acacia

It’s often said that evolution can be better than revolution, but I don’t think many people could have predicted Seiko to make a move like this. It was only four years ago that Seiko released the SPB143 and its variants to immediate success, basing the design on the original Seiko dive watch from 1965. Now, this new line of SPB watches has rendered them effectively redundant, tweaking the design in subtle ways to retrain its character but improve its performance. Seiko has definitely taken some risks, and time will tell if they pay off.

The case

seiko SPB453 dial wrist

It’s currently unclear whether or not Seiko intends to discontinue the watches nicknamed “20MAS” because of their 2020 release date, but the SPB455, SPB453, and SPB451 are all clear successors. There isn’t much reason for both of them to be sold at the same time, but I’m sure that the older models will still be available for a long time if you decide you prefer them. Getting into the crux of the matter, the case of the new models has been slightly altered in a few ways. The character of the 62MAS archetype is definitely still there, but it’s clearly a more refined take. The texture of the brushed surfaces seems to be a little bit deeper, which helps the polished facets on the sides of the lugs to stand out more.

seiko SPB453 case profile

The measurements have also changed, with a noticeable clipping of the lugs by 1.2mm to a total length of 46.4mm. It’s not a drastic change by any stretch of the imagination, but people with small wrists will likely be grateful for the adjustment. The 40mm diameter and 13mm thickness also represent a shrinking of 0.5mm and 0.2mm respectively, but those changes aren’t likely to be noticeable unless you hold the two side-by-side. Perhaps the most significant update to the case design is the water resistance increase from 200 to 300 metres. That probably won’t make much of a difference to most of the people who wear this watch on a daily basis, but its diving capabilities are certainly important to its history and professional reputation.

The dial

seiko SPB455 dial

The dial of the new 20MAS (or rather 24MAS) is where one of the most controversial changes has been made, and that’s the decision to move the date window to 4:30. The first iterations of the 20MAS didn’t even have a luminous marker at 3 o’clock before they were updated to include a small strip, and now it’s been determined that symmetrical hour markers all around the dial are necessary for perfect legibility. As someone who generally dislikes 4:30 date placements, I have to admit that this one has been well-integrated. The numerals are not at an awkward angle for reading, and the circular dial cutout is much less intrusive than a diagonal rectangle. The date wheels have also been colour-matched, so there’s no huge degree of contrast which distracts the eye.

seiko SPB451 dial

Change for the sake of legibility hasn’t been confined to the dial itself, as there has also been a subtle change to the aluminium bezel insert. Rather than the bold recessed numerals interrupting the flow of the minute markers, they have been shrunken slightly so that the markers can pass beneath them. This gives a much more accurate reading of an elapsed time measurement, whether that be a dive or something more pedestrian like a parking meter. You may also notice that the dial printing also says “3 days”, which is another one of the watch’s upgrades. Three dial colours are available at launch, with the SPB451 in deep blue sunburst, the SPB543 in matte black, and the special edition SPB455 in grey sunburst and gold highlights.

The movement

seiko SPB455 SPB453 SPB451 caseback

The new Seiko SPB455, SPB453 and SPB451 are all equipped with the calibre 6R55, which was originally billed as a high-performance calibre for King Seiko watches. In terms of specifications, the 6R55 is only marginally more impressive than the 6R35 it succeeds, having expanded the power reserve from 70 hours to 72. Although the extra few hours of power reserve is unlikely to make a difference in the experience of wearing an automatic watch, it does hit that psychological milestone of three whole days. It runs at a beat rate of 3Hz, and features a Spron 510 mainspring as well as magnetic resistance up to 4,800A/m.

The bracelet and strap

seiko SPB455 SPB453 SPB451 bracelet

The stainless steel bracelet which these watches come on is also very slightly modified, with smaller links that should flow more easily across most wrists. The 20mm lugs still feature drilled holes, so it will definitely retain strap monster status.

seiko SPB455 SPB453 SPB451 strap

Being a special edition, the SPB55 also comes with a grey woven NATO strap in the traditional Seichu style made from recycled ocean plastic.

The verdict

seiko SPB451 wrist

I’m quite surprised by this release from Seiko, as it feels much more like a V2 release from a microbrand than a new release from a huge corporation. Considering how popular the 20MAS watches have been, I’m sure that they could have continued to milk that set of specs for many more years. And yet, here we are with an updated version. It’s the simultaneous admiration and confusion which makes me struggle to know which version I prefer, and yet it’s safe to say that Seiko have justified the US$100 price increase from all the improvements.

Seiko SPB455, SPB453, SPB451 pricing and availability

The Seiko SPB455, SPB453 and SPB451 are now available from Seiko boutiques and retailers. Price: A$1,995, US$,1300 (SPB453, SPB451), A$2,350, US$1,400 (SPB455)

Brand Seiko
Model Prospex 1965 Heritage Diver’s Watch
Reference Number SPB455
Case Dimensions 40mm (D) x 13mm (T) x 46.4mm (LTL)
Case Material Stainless steel
Water Resistance 300 metres
Crystal(s) Sapphire
Dial Blue, black or grey and gilt
Strap Stainless steel bracelet, folding clasp
Additional recycled ocean plastic fabric strap (SPB455 only)
Movement 6R55, in-house, automatic
Power Reserve 72 hours
Functions Hours, minutes, seconds, date
Availability Available now
Price A$1,995 (SPB453, SPB451)
A$2,350 (SPB455)