All Seiko lines › Prospex › Sea
“MM200” / “Baby Marinemaster”
Seiko Prospex Sea diver's, 44 mm (6R15)
Collector nickname. Where the name comes from
5 versions of this watch are on Seiko's own sites right now, across 12 regions. Last checked Nov 13, 2026.
Estimated US price: About $1,050 to $1,330, converted from Seiko's list prices in EUR, GBP, INR and more.
Retailers ask: no retailer listing matched yet.
Photos are Seiko's own, shown from Seiko's sites. Click a photo to jump to that version.
- Calibre
- 6R15
- Case diameter
- 44 mm
- Thickness
- 12.7 mm
- Lug to lug
- 51 mm
- Variants listed now
- 5
- Regions
- 12
Listed means the watch was on an official Seiko regional site or store at the last check. It does not mean it is in stock, and it does not tell us whether Seiko is still making it.
Versions listed now
Same case and movement in every row. What changes is the colour, the strap or bracelet, the finish and where Seiko sells it. Seiko's spec sheets don't state dial colour, so a colour appears only where Seiko's US store tags one.
| Photo | Reference | Colour | Strap / bracelet | Case | Edition | Listed in | Seiko list price | Buy | ||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 | SPB087 Also coded SPB087J1 | Not published | Silicone 117 g | Stainless steel (super hard coating) with stainless steel bezel | Regular | 7 regions | 1,050 EUR Portugal · Nov 13, 2026 about $1,130 in US dollars | No seller matched yet | ||||||||||||||||||||||||||||||||
Where Seiko lists it (7 sites) and its list prices
Buying options (0)No seller offer has been matched to this exact variant yet. | ||||||||||||||||||||||||||||||||||||||||
 | SPB077 Also coded SPB077J1 | Not published | Not stated Clasp: Three-fold clasp with secure lock , push button release with extender 184 g | Stainless steel (super hard coating) with stainless steel bezel | Seiko Prospex The 1968 Automatic Diver’s Modern Re-interpretation | 6 regions | 1,350 EUR Portugal · Nov 13, 2026 about $1,190 in US dollars | No seller matched yet | ||||||||||||||||||||||||||||||||
Where Seiko lists it (6 sites) and its list pricesBuying options (0)No seller offer has been matched to this exact variant yet. | ||||||||||||||||||||||||||||||||||||||||
 | SPB079 Also coded SPB079J1 | Not published | Silicone 120 g | Stainless steel (super hard coating) with stainless steel bezel | Seiko Prospex The 1968 Automatic Diver’s Modern Re-interpretation | 5 regions | 950 EUR Portugal · Nov 13, 2026 about $1,050 in US dollars | No seller matched yet | ||||||||||||||||||||||||||||||||
Where Seiko lists it (5 sites) and its list pricesBuying options (0)No seller offer has been matched to this exact variant yet. | ||||||||||||||||||||||||||||||||||||||||
 | SPB083 Also coded SPB083J1 | Not published | Not stated 186 g | Stainless steel (super hard coating) with stainless steel bezel | Regular | 4 regions Brazil, Indonesia, Thailand, UK | 1,060 GBP UK · Nov 13, 2026 about $1,320 in US dollars | No seller matched yet | ||||||||||||||||||||||||||||||||
Where Seiko lists it (4 sites) and its list pricesBuying options (0)No seller offer has been matched to this exact variant yet. | ||||||||||||||||||||||||||||||||||||||||
 | SPB097 Also coded SPB097J1 | Not published | Not stated | Not stated | Regular | 2 regions Hungary, Italy | 1,200 EUR Italy · Nov 13, 2026 about $1,330 in US dollars | No seller matched yet | ||||||||||||||||||||||||||||||||
Where Seiko lists it (2 sites) and its list pricesBuying options (0)No seller offer has been matched to this exact variant yet. | ||||||||||||||||||||||||||||||||||||||||
Where to buy
No retailer listing has been matched to a version on this line yet.
Estimated US prices use Seiko's US list price where there is one. Otherwise they are the middle of Seiko's list prices in other countries, converted at rates dated Nov 12, 2026 from ExchangeRate-API (free open endpoint). Those list prices include each country's sales tax, so a converted figure usually runs higher than a US price would. Retailer prices are asking prices on the date shown, not sold prices, and leave out shipping, tax and import charges.
The build
| Movement | Automatic with manual winding | Seiko product page |
|---|---|---|
| Functions | Stop second hand function Date display | Seiko product page |
| Power reserve / battery | Approx. 50 hours | Seiko product page |
| Water resistance | 200m / 660ft diver's | Seiko product page |
| Crystal | Sapphire crystal | Seiko product page |
| Lug width | 20 mm | Seiko product page |
| Seiko case codes | 6R15-04G0, 6R15-04J0 | Seiko catalog data |
Why these share a page
Every version here is published by Seiko with calibre 6R15 and either the same Seiko case code or the same case size. 10 reference codes lead to this page.
What people call it
A name is shown only where a source ties it to a reference on this page. Collector nicknames are not Seiko's names unless the row says so.
| “MM200” | Collector nickname. Source names SPB077. “In the end, the Seiko Prospex SPB077 “MM200” is a bit of an odd bird.” | Worn & Wound read 2026-11-12 |
|---|---|---|
| “Baby Marinemaster” | Collector nickname. Source names SPB077, SPB079. “References SPB077 (black on bracelet) and SPB079 (blue on rubber) were introduced and thus was born the “Baby Marinemaster”.” | Fratello read 2026-11-12 |
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