SpecStudio
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Seiko Monster Automatic 200M
Ref. SRP315J1 · Diver
Stock unknown
Case
- Diameter
- 42mm
- Material
- Stainless Steel
- Finish
- Brushed and Polished
- Water resistance
- 200m
- Caseback
- Solid
Crystal & dial
- Crystal
- Hardlex
- Shape
- Flat
- Dial colour
- Orange
- Indices
- Applied
Movement
- Caliber
- Seiko 4R36
- Type
- Automatic
- Beat rate
- 21,600 vph
- Power reserve
- 41h
- Jewels
- 24
Seiko
Seiko's day-date automatic caliber and the in-house branded version of the NH36 with stricter quality control and finishing. The additional day wheel over the 4R35 adds the day-of-week complication without changing the movement dimensions. Found extensively in the Seiko 5 Sports and Prospex lines, it offers Seiko's proven reliability with the convenience of day-date display at a mainstream price point.
Monster collection · 2 watches
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Retail stock & market context
Seiko on the secondhand market
+8.1%
2026 so far · +3.6% to +12.7% · 80 matched watches
In line with the index
Divers as a group: +6.3% · 305 matched watches
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In a nutshell
The Seiko Monster Automatic 200M (ref. SRP315J1) is an automatic diver watch, with a 42mm stainless steel case, powered by the Seiko 4R36 movement and a 41-hour power reserve. Water resistance is rated to 200m, under a hardlex crystal.
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