Wednesday, July 25, 2018

Seiko Prospex SLA025J1 (or SBEX007) Hi-Beat 300 Meter Limited Edition Dive Watch - A new love affair, A Review (plus Video)

In 2017, Seiko re-issued its iconic dive watch, the 62MAS in the form of the SLA017 (or SBDX019). This year the brand celebrates the 50th anniversary of another icon, the first hi-beat dive watch, the Seiko 1968 Reference 6159-7001. This original watch was very significant in many ways. In that year, Seiko released a diver that had doubled its dive rating, drastically increased legibility and timing precision, added an automatic movement, and offered an innovative and unique design. It wasn’t the first Seiko diver, but it was definitely the most consequential, and helped lay the groundwork for many future iconic models from the brand.

When it was presented at Baselworld 2018, I was very excited and it immediately joined my 'must have' list. I started to put my name down on a number of waiting lists managed by friendly Seiko authorised dealers. Since this is a limited edition model with only 1,500 units, demand is expected to be fierce and to hedge my bets, I got on a few waiting lists. The first that calls me will get my business.

The watch has two references; the SLA025 is the reference for the model sold on the international market while the SBEX007 is the reference for the model sold solely for the Japanese Domestic Market. There will be 1,500 examples of the former and 1,500 examples of the latter. Both are made in Japan with the only difference in the reference and serial number stamped at the back of the casing.

I was informed that Seiko will start shipping the watches sometime in August. My local Seiko dealer also told me the same. However, in early July, news had it that shipment will be made earlier than scheduled. In fact, I got the call from my local dealer about the timepieces having arrived in Thong Sia (the main Seiko dealer for Malaysia and Singapore) and waiting to be delivered to key distributors. As mentioned earlier, who calls first gets my business and I immediately committed to get one from the local dealer.

The Genesis

The SLA025 is a modern re-interpretation of Seiko's iconic 6159-7001 dive watch. Launched in 1968, the 6159-7001 was Seiko’s first attempt at a professional dive watch. In fact, it was Seiko’s third diver after the iconic 62MAS (or 6217-8001) and 6215-7001. The watch set a new benchmark for all watch manufacturers, featuring a solid monocoque case design which allowed for an impressive water resistance rating of 300 meters, doubling any professional dive watches in the market at that time. As an icing the a great cake, Seiko also equipped the 6159-7001 with a hi-beat Grand Seiko automatic movement running at 36,000 BPH for better accuracy and reliability.

The original Reference 6159-7001

Unfortunately, the watch had a relatively short production span of just two years. It has been speculated that the manufacturing process required to ensure it can withstand 300 meters of water pressure was too elaborate and expensive to sustain series production without revising the price upwards considerably (In reality, Seiko does not aim to match the price strategy of European watchmakers. The production costs of the 6159-7001 would require European style pricing. Between that and keeping to its policy, Seiko decided to keep sacred it policy which meant the end of production of the 6159-7001 after just two years). Please note again that this is purely speculative. Seiko remains silent on this issue. Whatever the true reason, the 'mystery' did help pushed the market perception of the brand's technical prowess to a higher level.

Before we start the review, let us appreciate the history behind the concept of Seiko’s dive watches. Since 1965, Seiko has been manufacturing dive watches. Below is a graphical time on the achievements of Seiko on just this product line.

The Watch

The SLA025 is officially called, in full, the 1968 Automatic Diver’s Re-creation Limited Edition SLA025 (not sure whether it is the same for the JDM version SBEX007). The case is made out of one solid piece of 316L stainless steel, drilled out with only two openings: the front for the dial and the hole from the crown stem. This means it does not have a removable case-back to access the automatic movement. If you need to work on the inside of the watch, the only access it through the front.

The SLA025 is 44.8 mm wide (excluding the crown). Lug-to-lug length is 51.4 mm while its lug width is 19 mm. As a tool watch, it has a very respectable thickness of 15.7 mm. Paired with silicone straps, it is capable to fit a person with a maximum wrist circumference of 205.0 mm (this is more than sufficient for a large sized professional diver wearing a full body wet-suit). Overall weight is approximately 147 grams.

Other general features of the watch are the 3-hands, the date aperture at 3 o'clock, the crown at 4 o'clock, the angular lugs, the unidirectional bezel and the domed sapphire crystal.

The Dial

The dial of the SLA025 has a matte black “gilt” styling and is nearly identical to the original model. It comes with applied white circular and quadrilateral hour markers filled with Seiko Lumibrite and outlined with gold colouring. The 12 o'clock marker which looks like a 5-sided obelisk is the largest with the luminous paint (Lumibrite) separated into two halves by a frame line gold colouring running through the middle.

The dial is set deep into the watch which provides a visual depth to the presentation. The sloping chapter ring has the line minute markers in white that further enhances the illusion.

Like the original, the 3 o’clock hour marker has been replaced with a gold-outlined date aperture. The date wheel has a white background with black numbers which should provide some semblance of consistency with the other hour markers. I personally would have preferred a real hour marker be put at 3 o'clock and place the date aperture somewhere else that would not disturb the symmetry of the dial. I know this will make SLA025 visually different than the original but why not if our purpose is to re-imagine SLA025 minus the mistakes of the old?

In terms of texts and logo, at the upper quadrant of the dial is the Seiko logo with the words “Automatic” and “Hi-Beat” below it, and toward the lower quadrant of the dial is printed “Professional”, “300m” as well as some small manufacturing coding at the dial peripheral. The only aesthetic differences between the vintage and contemporary models are found in this bottom section. Instead of just "300m" on the SLA025, the original has "WATER 300m PROOF" and an additional line of a vintage Seiko dive logo. Although the SLA025 is listed as part of Seiko's Prospex line, the logo of this line was not added to the dial (instead of the vintage Seiko dive logo, it is conceivable for Seiko to replace it with the Prospex logo instead). I wonder why Seiko decided against adding the newer logo?

The SLA025 also features a hands set which is visually identical to the original. Beveled and polished, the hands appears to have some illusion of weight to them by virtue of not extending the painted region all the way back to the stem (especially the hours hand). I especially like the seconds hand with the “red dot” added next to the painted section. As always, Seiko has been very generous with the amount of LumiBrite paint put on the hands.

The watch comes standard with a tall uni-directional stainless steel bezel with black aluminum insert. The bezel has a 60-minute scale and a golden track and numerals, designed just like the original. The customary luminous pip is provided at the 60 minute point. The bezel does move in a 120-click increment for a full rotation (I believe the original has a 60-click system for a full rotation). The sides of the bezel is coin-edged which facilitate grip.

Although the specifications says the SLA025 has a dual curved sapphire crystal glass over the dial, you can't see the dome shaped crystal properly. This is because it is sunken within the tall bezel. The bezel definitely will protect the domed sapphire crystal from side impact. Moreover, the sapphire crystal has an anti-reflective coating on the inner surface.

The screw-down crown is positioned at 4 o’clock. It is similar to the original, sterile without any logo or etchings.

In the picture above you can see the beveling of the watch casing from the centre line of the watch casing. Very angular and rather stunning in my opinion.

The lugs on the SLA025 is short and curved towards the wrist. This reduces the overall length of the watch to enable better contact with wrists with smaller dimensions. You will also able to see the pass-through lug holes drilled at both ends of the casing to facilitate strap replacement.

The back of the watch casing is flat. In fact, it is one solid piece. As such, there is a lot of surface area for Seiko's designers and artisans to play with.

However, in keeping with the styling of the original 6159-7001 (picture from an example taken from the internet), Seiko decided to follow the same theme. Although it looks similar, some interesting takeaways can be observed.

Once again, the vintage Seiko dive logo was not replaced with the newer Prospex logo. I have asked the question earlier; why not make the change? I speculate that the reason Seiko decided against the Prospex logo is probably due to the negative feedback received about the prolific additional of the logo on new timepieces under the line (the issue is the size of the logo - too prominent on the dial surface). If Seiko sized the new logo in a similar manner, I don't think people will complaint as much.

Seiko took the effort to indicate that the watch is a mixed-gas capable dive watch i.e. the SLA025 is capable to be used in technical diving situations. This is a term used to describe all diving methods that exceed the limits imposed on depth and/or immersion time for recreational scuba diving. Technical diving often involves the use of special gas mixtures (rather than compressed air) for breathing.  While the recommended maximum depth for conventional scuba diving is 40 meters, technical divers may work in the range of 50 meters and beyond.

The SLA025 has a flat surface for the back whereas the 6159-7001 has a circular indentation around the back. I suspect the indentation creates the base where the Calibre 6159A sits on. For the SLA025, the mounting points for the Calibre 8L55 is attached from the inside of the casing.

The Movement

The caliber powering the watch is the Seiko 8L55. This is the brand's hi-beat automatic movement running at 36,000 BPH or 5 Hertz. It has the spring power to last for approximately 55-hours with hacking and manual winding capabilities. Apart from the three hands, the caliber also supports a date complication. The movement is handmade by elite watchmakers in the Shizukuishi Watch Studio, Seiko's exclusive manufacturing outfit dedicated to high-end Seiko timepieces.

The 8L55 is similar to the famous 9S85 Grand Seiko caliber apart from being less decorated and more tool-like in appearance; more suited for usage in watches with no display case-back. Although the movement has a manufacturer's accuracy rating of -10/+15 seconds per day which is rather standard and not as good as one would expect of a high-end Seiko movement, the actual accuracy will surpass its manufacturer's rating very easily. Definitely an 'under-promise' public relation strategy Seiko is known for.

The Silicone Strap

The watch casing is paired with a Seiko silicone strap. The strap has a waffle-style texture with a simple and unsigned stainless steel buckle. The strap guide is metal, painted black and signed with the brand name. The strap is capable of supporting a wrist size of 205.0 mm in diameter.


I was quite happy that Seiko chose silicone instead of rubber. It is more flexible, softer and (should) last longer than rubber. My only comment is that Seiko should have provided extra straps for customers. Since this is a limited edition timepiece, a special watch box with extra straps and a strap replacement tool would be a welcoming addition to the package. Since the vast majority of new owners of the SLA025 will be 'desk divers' anyway, the availability of a branded leather strap can provide a better styling for use in formal settings. In this case, perhaps Seiko could provide a leather strap (for formal settings) and a nylon strap (for sports settings) instead of just the silicone strap (for water settings).

The Wearing Experience

The watch wears well despite it size. The short angular lungs as well as the silicone strap keeps the watch firmly on the wrist. Due to the softness of the silicone strap, you don't realized how firmly the strap clings to your wrist until you take it off - you will be able to see an imprint of the strap's texture on your skin.

The watch could be tad too tall to wear with formal wear. As you can see in the photos above, if your cuffs are close fitting, it may not slip under it. Below is a video of the watch on my wrist.

As a suggestion, a leather strap with deployant clasp would make it more fashionable.


Despite it's size, I love this watch. It rekindled my love affair with sports and diving watches when I first got started into the watch collecting hobby. I prefer to buy new watches instead of buying vintage watches and any example of a re-interpretation of an old icon is something that I would look forward to.

Looking at the iconic dive watches by Seiko, the next re-interpretation that I be keenly waiting would be the digital dive computer of the year 1990 and year 2000.

The Reveal

This is the first time that I got a timepiece from Seiko's boutique shop in Mid Valley.

Due to the model's uniqueness, I was made to understand that Thong Sia, Malaysia's Seiko distributor was only allocated a couple of pieces out of the 1,500 made. All the units were distributed to the Grand Seiko Boutique Shop in Mid Valley, Kuala Lumpur.

It is interesting to note that the paper bag given is simple yet elegant. The bag has a off-white papyrus texture with the brand printed in silver.

The Grand Seiko Boutique Shop also gave me a few free gifts with the purchase. Although I don't want to be seen as petty, I expected more from the shop considering the price I paid for the watch. To them, four branded shopping bags are all what they can give to their customers.

The watch is packed into a package that consists of three layers. The first layer is the packaging box that consist of a white cardboard slip. It has a series of warnings on the top part of the box in many languages that remind the dealers to remove this part of the box before selling it to the customers.

I personally would prefer to keep this sleeve when I buy the watch as it offers protection to rest of the packaging during transit.

Taking the sleeve of you will find the outer watch box in grey. Made out of hard cardboard box, it has the Seiko brand printed in silver at the top of the box. This box opens up to reveal the main watch box as well as a slot at the bottom for the guarantee document and manual.

The main watch box is wrapped in nice rice paper (not sure if this is correct but it feels like rice paper). To lift the main watch box from the hard cardboard box, one just need to pull the ends of the rice paper to take it out.

The main watch box is made out of a more hardy material. It has a leathery surface (I don't think it is real leather) with a dark shellac finishing around the horizontal center of the the watch box. It hinges on the back and when opened, it shows the watch sitting on its cushion in a slot in the middle of the box.

The inner surface of the watch box is also shellac with one other space for storing anything else. You will also see the logo printed on the shellac surface in white as well as the Prospex sub-brand and logo on the top inner surface of the main watch box.

If I was given a choice, I would have provided extra straps (as well as a place to put them) for users to choose from. Granted the SLA025J1 is supposed to be a re-creation of a cult classic Seiko diver, the Reference
6159-7001, Seiko need not have 'strictly' followed the script. Chances are, buyers of this watch will not be using it as intended. In fact, more likely, the owners of the SLA025J1 will be using it more in formal settings instead. Therefore, apart from the standard silicone strap, it would be nice if Seiko also provide options like a NATO fabric strap and a sports leather strap for users (to make it even sweeter, Seiko can also throw in a signed tool to facilitate strap changes 😀). For me, a leather strap would be more useful since I am in an office environment most of the time.


Case Material: Stainless steel case with super-hard coating (Diashield)
Polishing: Zaratsu method
Glass Material: Dual curved sapphire crystal glass
Band Material: Waffle-style black silicone
Strap length: 205.0 mm
Glass Coating: Anti-reflective coating on inner surface
Illumination: Seiko's proprietary Lumibrite luminous compound
Thickness: 15.7 mm
Diameter: 44.8 mm
Lug-to-Lug: 51.4 mm
Lug Width: 19.0 mm
Bezel: Unidirectional rotating bezel; 120-click for full rotation
Crown: Screw-down; sterile
Complications: 3-hands; date
Caliber: 8L55; automatic with manual winding mechanism; stop second hand function
Frequency: 36,000 BPH
Jewels: 37
Accuracy: -10 to +15 seconds per day (when static)
Magnetic Resistance: 16,000 A/m
Power reserve: Approximately 55 hours
Weight: 147 gm
Water Resistance: 300m professional diver's watch for saturation diving
Other Features: "LIMITED EDITION" on the case back; 1,500 examples only
MSRP Japan: YEN550,000
MSRP Malaysia: RM24,950.00

Photo Gallery


  1. Mr. Easternwatch,
    Very nice review and well said. Do you have any idea or information regarding how many component on this particular model (SLA025) and what material that was use for the bezel?
    Your assistance is greatly appreciated.

  2. Hi, I'm looking for this 1968 re-creation model. Any help would be much appreciated. Thank you.



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