Introducing The Seiko Prospex Black Series SLA035J1 & SPB125J1 Limited Edition Watches


Seiko is a brand that is well known for producing some of the best value-oriented dive watches in the industry. For 2020, the Japanese watch giant is expanding its Prospex collection by adding new variations of two of its popular dive watches. A part of the Seiko’s new Black Series, the SLA035J1 and SPB125J1 are fully dressed in black to provide a distinctive and stealthy take on the Marinemaster and Sumo.

Whilst the SLA035J1 and SPB125J1 are very different watches, they do have a few things in common as a part of the Black Series. On the dial front, both watches have been presented with a Matt black dial, applied hour markings, chunky handsets with bright and colorful highlights and a date window at 3. Furthermore, following the all-black theme, the entire cases including the bezel and the crown have been given a special black coating. And finally, to complete the tactical look, both watches would come attached to black rubber straps. Now onto the individual references.


Having a case with a diameter of 45mm, a thickness of 12.9mm and a lug to lug distance of 53mm, the SPB125J1 is dimensionally the same as the Sumo. Sitting on top of the case is a uni-directional dive time bezel with an aluminum insert that features the first 20 minutes of the markings in grey and the rest in black. The case is water-resistant to a healthy 200 meters. The face is where Seiko has made a few significant changes as compared to the regular version of the Sumo. Firstly, the applied markers and the handset has now been filled with custard colored luminous paint instead of white, and the minute hand has now been outlined in orange adding a nice splash of color to the dial. Powering the watch is Seiko’s relatively new in-house automatic caliber 6R35. This movement operates at a frequency of 3Hz and offers a healthy power reserve of around 70 hours. The production is limited to 7000 pieces worldwide and the retail price has been set at EUR 829.


Based on the Seiko SLA021, a refreshed version of the Marinemaster, the SLA035J1 measures 44mm in diameter has a thickness of around 15.9mm and a more manageable lug to lug distance of 50.2mm that would make this one would sit comfortably on a wide variety of wrists. Also, as this is more of a luxury offering, the case on this one has been finished using Seiko’s famous Zaratsu polishing technique. Sitting on top is a heavily domed sapphire crystal that is held securely in place by a black ceramic uni-directional bezel. The dial on the Marinemaster is and has always been one of the cleanest, legible and most refined among all Seiko divers and nothing much has changed on the SLA035J1, except for one small detail. The seconds hand has now been presented in a bright red shade to add a nice pop of color to the dial and provide a great contrast against the black background. Driving this watch is Seiko’s in-house Caliber 8L35. This is a top-notch automatic movement that operates at a frequency of 4 Hz and offers a power reserve of 50 hours keeping time accurately between -10 and +15 seconds a day. The SLA035J1 is limited to just 600 pieces and would retail at EUR 3,100.

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