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Seiko Presage SSA425 Open Heart vs Seiko Prospex Samurai SRPF03
Seiko's timepiece meets Seiko's diver
Quick Verdict
The Seiko Presage SSA425 Open Heart ($250–$500) and Seiko Prospex Samurai SRPF03 ($250–$500) are closely matched timepieces at similar price points. The Presage SSA425 Open Heart emphasizes Seiko In-House Automatic engineering while the Prospex Samurai SRPF03 focuses on Japanese Movement craftsmanship.
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Specifications Compared
| Feature | Seiko Presage SSA425 Open Heart | Seiko Prospex Samurai SRPF03 |
|---|---|---|
| Price | $250–$500 | $250–$500 |
| Case Size | 40.5mm | 43.8mm |
| Movement | Automatic Caliber 4R38 | Automatic Caliber 4R35 |
| Caliber Type | Seiko In-House Automatic | Seiko Automatic, hand-winding and hacking |
| Power Reserve | 41 Hours | 41 Hours |
| Water Resistance | 50m (5 ATM) | 200m (20 ATM) |
| Crystal | Hardlex Crystal | Hardlex Crystal |
| Case Material | Stainless Steel | Stainless Steel |
| Origin | Made in Japan | Japanese Movement |
Category-by-Category Analysis
Design & Aesthetics
Seiko's design language vs Seiko's approach
The Seiko Presage SSA425 Open Heart features a Stainless Steel case at 40.5mm with Hardlex Crystal protection. The Seiko Prospex Samurai SRPF03 offers Stainless Steel construction at 43.8mm with Hardlex Crystal. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Automatic Caliber 4R38 vs Automatic Caliber 4R35
The Presage SSA425 Open Heart runs the Automatic Caliber 4R38 (Seiko In-House Automatic, 41 Hours power reserve) at 21,600 vph (3 Hz) frequency. The Prospex Samurai SRPF03 uses the Automatic Caliber 4R35 (Seiko Automatic, hand-winding and hacking, 41 Hours reserve) at 21,600 vph (3 Hz). Power reserves are closely matched.
Wearability & Fit
40.5mm vs 43.8mm — different wrist presence
At 40.5mm, the Presage SSA425 Open Heart wears more compactly on smaller wrists compared to the Prospex Samurai SRPF03 at 43.8mm. Water resistance differs: 50m (5 ATM) vs 200m (20 ATM).
Value & Cost of Ownership
Same tier — different value propositions
The Seiko Presage SSA425 Open Heart sits at $250–$500 and the Seiko Prospex Samurai SRPF03 at $250–$500. On the specs that outlast any price: the Presage SSA425 Open Heart uses Hardlex Crystal with 41 Hours, against Hardlex Crystal and 41 Hours on the Prospex Samurai SRPF03. Service intervals are typically 5-7 years for both.
Water Resistance
50m (5 ATM) vs 200m (20 ATM)
The Presage SSA425 Open Heart is rated to 50m (5 ATM) while the Prospex Samurai SRPF03 handles 200m (20 ATM). The Prospex Samurai SRPF03 offers superior water resistance.
Our Verdict
Seiko
Presage SSA425 Open Heart
Choose the Seiko Presage SSA425 Open Heart if you prioritize Seiko In-House Automatic engineering, Made in Japan craftsmanship, and 50m (5 ATM) water resistance. At $250–$500, it delivers Automatic Caliber 4R38 with 41 Hours power reserve.
Check Price on AmazonSeiko
Prospex Samurai SRPF03
Choose the Seiko Prospex Samurai SRPF03 if you value Seiko Automatic, hand-winding and hacking technology, Japanese Movement heritage, and 43.8mm proportions. At $250–$500, the Automatic Caliber 4R35 with 41 Hours power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Seiko Presage SSA425 Open Heart and Seiko Prospex Samurai SRPF03 represent two distinct approaches to fine watchmaking — the Seiko bringing Made in Japan tradition while Seiko delivers Japanese Movement engineering.
Frequently Asked Questions
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How This Page Was Made
Our comparisons are generated from a hand-maintained specification database and reviewed under our editorial standards. We use AI tools to assemble pages from that data. We don’t invent specs: every number traces back to the database, and when we correct an entry, the fix is applied site-wide. As an Amazon Associate, The Horologist earns from qualifying purchases.