Hands on Review of the Baby MM300 SBDC063/SPB079….Sleeper hit!

Since time immemorial (or what you might know as 10 years in my watch collecting hobby), I’ve always lusted for the SBDX001, or as it’s more fondly known, the MarineMaster 300 or MM300 for short. However, several things had always stood in the way such as how high it sits on my 6.5in wrist, its considerable price and finally its discontinuation first as the SBDX001 some time back in 2015 and then its replacement SBDX017 earlier this year. Everything seems to conspire against me ever owning a MM300!

SBDX001 – The Classic. Photo from W&W

It was then a delight to me than Seiko decided to launch a baby version of the SBDX001/17 in the guise of the SPB079 (International) / SBDC063 (JDM) at Basel 2018. Separately, I was of course delighted that they chose to launch the SLA025 which is a much more faithful interpretation of the historical 6159 diver, but the price range was a bit too rich for the missus. However, kukos to Seiko for launching the SLA025 with the correct 8L55 movement which beats at 10bps, which was exactly how fast the original 6159 caliver was beating at!

Before continuing with my hands on review, I need to let readers know that I have not purchased any of the new Seiko models in the last 3-4 years. Yes, its unimaginable, but I do not have a single contemporary Turtle in my collection. I even skipped the well-built Samurais that were launched in the last 1-2 years. There were two main drivers for this. Firstly, I had started to look backwards into Seiko’s history and started purchasing their classic vintages instead. Secondly, and this is just my personal view, Seiko has been steadily increasing their prices and no longer providing as much value as they used to.

Stock Photo from Seiko Japan

So why did I decide to buy the SBDC063? Simply because it was so DAMN good looking at a price that I could stomach. Please note that I did not actively seek out this watch. When I first saw its stock photos during the Basel 2018 I was unimpressed, which was normal given how bad Seiko’s stock photos usually are. The price (JPY 90,000 for the JDM and EUR 900 for the international model) and radical new hand set was not exactly palatable to me at that time either.
However, in the middle of July, I was watch shop hopping with several watch kakis (a local slang used in Singapore for friends) and dropped by the Gnomon Watch storefront. Gnomon showed us the SBDC063 and told us that it was just made available here in Singapore. The rest as they said was history.

I was absolutely and totally smitten with the blue steel bezel, which I believe is rarely seen in dive watches. The bezel catches the light and reflects everything around it beautifully. The font used was close but not exactly the same as the original but Seiko did away with marking out the first 15 minutes of the bezel, thus ensuring that the bezel was perfectly balanced. The unsigned crown was without any crown guards just like its predecessor. Together these 2 factors bring to mind the classy skin divers of years gone by, when divers remained smart and slim enough to accompany one from the boardroom to the sea.

I bought my SBDC063 stock with its silicon strap and metal keeper/buckle, but I had also separately purchase the stainless steel bracelet that came with its brother, the SBDC061/SPB077. However, as you can see from the photos below, I quickly swapped out the stock silicone strap for one of w&w Cordovan NATO Strap.

The Bezel

Let’s face it. This is absolutely the most gorgeous bezel I have ever encountered in person. The turquoise green/blue bezel is an absolute stunner, not to mention how reflective it is in person. This was definitely not captured in the stock photo but would have easily be the main selling point of this baby MM.

Seiko did not explicitly state what the bezel insert was made of, but it definitely does not feel like old school aluminium. It had the sheen of the ceramic similar to my SAEH005 on the right above, but it feels like good old steel. How did they make it so blue and so blinge-ly? God knows!

The bezel on the baby MM is not exactly blue once I compared it to my other “blue” watches, but there’s a dash of green in it, which makes it more of a turquoise colour.

The pip at 12 o’clock sits recessed on the bezel within its own inverted little triangle, which ensures that it’ll not get scratched easily. Once again, just look at the reflections in the bezel!

Alongside the bezel insert which I have been gushing about in the last 2-3 paragraphs, the bezel itself is 3mm high and serrated all around, similar to a coin edge bezel. The bezel is of the 120 click variety and it’s while it’s not the best rotating action Seiko had to offer, it’s far from being the worst.

The bezel surface is not flat but slopes downwards from the centre to the edges very subtly.

The Case

The case is 51mm high, 44mm from side to side and just 13.1mm thick, which is slightly smaller than its big brother the SLA025 in height and width but substantially thinner by 2.6mm and what a difference that makes for wearability! The main driver for this reduction in height is that the baby MM has a screw down case back while the MM300 has a monobloc case.

The top of the case is a circular brushing that you can barely observe in the photo above, with mirror finishing everywhere else.

Now the higher end SLA025 came with Zaratsu polishing on its case, which is only expected given its price point. I’m fairly certain that the baby MM did not enjoy the same loving care to its case finishing, but its mirror polishing is still nothing to be snuffed at, especially at it’s price point.

In the above photo, if you observe the bottom left lug of the Ananta SAEH005 (on the right), the shiny edge is Zaratsu polished and surrounded by 2 brushed planes. Contrast that with the baby MM on the left and you’ll notice immediately how much finer and brighter Zaratsu polishing is.

In the two photos above, I tried to illustrate two different styles that Seiko adopted in the design of the sides of the watch case.
In the above photo which had the baby MM in the foreground, the sides of the case flow organically from the top plane, nearer to the bezel, downwards to the bottom plane before it connects to the case back. It looks so dark on the bottom plane because the case was reflecting the wood of the table perfectly.

In the second photo, which had the baby MM in the background, the side of my other watch (SARN001) had taken a more angular approach to the sides of the case, creating many more planes/angles in the case.

In the two photos above, I tried to illustrate two different styles that Seiko adopted in the design of the sides of the watch case.
In the above photo which had the baby MM in the foreground, the sides of the case flow organically from the top plane, nearer to the bezel, downwards to the bottom plane before it connects to the case back. It looks so dark on the bottom plane because the case was reflecting the wood of the table perfectly.

In the second photo, which had the baby MM in the background, the side of my other watch (SARN001) had taken a more angular approach to the sides of the case, creating many more planes/angles in the case.

The crown located at the 4 o’clock position is absolutely gorgeous without any offending crown guards to break the alluring curves of the sides of the case. I am torn between having the crown fully polished and having it signed with a “S”, but I have to agree that Seiko took the conservative and right approach of having it unsigned, similar to its vintage inspiration.

The Dial

There’s a mix mash of vintage and modern elements here. The hour markers are faithful to the original, being gorgeous pools of creamy lume at all the markers except the compass points.

The date window with its white border sits at the 3 o’clock position while bullet markers reside at the 6 and 9 o’clock position, while a double bullet sits at the twelve o’clock marker. All the hour markers are properly bordered by steel outlines, which helps to add an element of depth to an otherwise matt black dial.

Unlike the original, the markers have white accents rather than the period correct gold accent. Thankfully, this matches with the white bezel markings. Unlike other major watch manufacturers, Seiko did not choose to use faux vintage lume, but kept to their Lumibrite paint.

The decidedly modern elements are the printing on the dial, especially that “X” which proudly proclaims the baby MM to be part of the Prospex family. Fortunately for people forking out good money for the SLA025, Seiko wisely decided to leave this “X” out.

There’s no applied Seiko logo to be found here.

The Contentious Handset

Let’s talk about the elephant in the room.

The handset.

It’s either a deal breaker for most people, or they just have to suck it up and live with it. I belong to the latter camp. There might be a third camp of people who love this new hand set, but I have not met any of them yet.

They are not your typical monster hand set, in fact they are much higher quality than that, being made of steel and outlined nicely. They also have blacked out middles and counterpoints. Of course, nothing would have beat the original handset, but I do understand that Seiko had to ensure that the re-interpretation had to be sufficiently different from the SLA025 while still retaining the Seiko DNA. Let’s put it this way, no one will mistake this for a Rolex or a Tudor from afar.

The Movement

The uber reliable 6R15 powers this baby MM. It’s a cut above the regular 4R movement that powers the Turtles/Samurais, with a better regulated movement (+25/-15sec / day) and longer power reserve (50 hrs vs 42 hrs). Unfortunately, it still beats at 6bps, which is not a deal breaker for me. Mine example runs within 5 seconds a day over 24 hours, which is good enough for me.

It is, however, a far cry from the 8L35 which powered the SBDX001/017, which is really a less decorated 9S movement, but this would increase the price easily by 1 fold or more.
No complaints here. What you pay is what you get.

Other factors

I would like to bring up the use of the Diashield coating that was advertised with this pair of watches, which supposedly brings the hardness of the steel up to 2-3x that of the normal stainless steel.

Does it work? Hell yes.

I’ve wore this watch for a day to the office before writing this review. It was passed around to many colleagues and came back to me with nary a scratch on its shiny case at the end of the day.

Before that, I had experience with Diashield with the titanium Seiko Shogun (now known as the SBDC029), which I had for a year before trading it away. During that year, there was no scratches whatsoever on its case and bracelet, and that was nearly 6 years ago. Given that many years have since past, I’m certain that Seiko would have improved on its Diashield technology by then.

The other major improvement that the baby MM had over the older MM300 is that it finally comes with a sapphire crystal with anti-glare coating. Previously the MM300 came with Hardlex crystal, which was a real head scratcher given it’s price point, but I’m glad that this was remedied in the baby MM.


I am smitten.

Is it an expensive Seiko? Yes of course it is. However, taken in reference to all the new releases it is approximately 50% more expensive for a sapphire crystal, movement upgrade (6R vs 4R), and Diashield coating than a limited edition Seiko Turtle (eg the PADI SBDY017). Plus the fact that it’s a modern re-interpretation of the MM300 makes this buy a no-brainer.

As I like to say, I have skin in the game, because the watch used in this review belongs to yours truly.


5 thoughts on “Hands on Review of the Baby MM300 SBDC063/SPB079….Sleeper hit!

  1. Pingback: Seiko x RISINGWAVE Transocean Automatic Dive Chronograph 8R49 SBEC003 | musingsofawatchaddict

  2. Thanks for the review. Got one myself and strapped it to a waffle strap that made it look more like the sla.

    All the best

  3. Nice review! Have come across your page as I am torn between all these MM200 variations (all black, the one you review here, Malta sunset ed., Blue hole ed., Green sunset ed., PADI ed.) aaaand the SPB143/5/7/9, the smaller diameter 62MAS options, which are not out yet (outside Japan) and which could be the nice alternative as well.

    One thing to note though — MM200 do have Zaratsu polishing, confirmed by a local Seiko boutique, so I guess your comments on the polishing quality are somewhat biased 🙂

    • Hi Nick,

      I’ll be sceptical about what the boutique staff tell you as not all of them are WIS like us. Unless there’s official marketing materials about the MM200 having Zaratsu polishing, I’ll be conservative and discount it.

      Zaratau polishing is a highly tedious and manual process which adds on cost which is one reason I’m sceptical that the MM200 has it.

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