Casio MTP-S120L Solar Field vs Seiko Prospex Samurai SRPF03
Casio's field watch meets Seiko's diver
Quick Verdict
The Casio MTP-S120L Solar Field ($100–$150) offers Casio Tough Solar Quartz precision in the tier below the Seiko Prospex Samurai SRPF03 ($250–$500). The MTP-S120L Solar Field measures 44.5mm and is rated 100m (10 ATM). The Prospex Samurai SRPF03 counters with Japanese Movement craftsmanship and 200m (20 ATM) water resistance. Both are exceptional watches for their respective tiers.
Transparency — We earn a small commission on purchases made through our Amazon links. This doesn't affect our editorial independence.
Specifications Compared
| Feature | Casio MTP-S120L Solar Field | Seiko Prospex Samurai SRPF03 |
|---|---|---|
| Price | $100–$150 | $250–$500 |
| Case Size | 44.5mm | 43.8mm |
| Movement | Solar-Powered Quartz | Automatic Caliber 4R35 |
| Caliber Type | Casio Tough Solar Quartz | Seiko Automatic, hand-winding and hacking |
| Power Reserve | Months on a full solar charge; no battery replacement | 41 Hours |
| Water Resistance | 100m (10 ATM) | 200m (20 ATM) |
| Crystal | Mineral Crystal | Hardlex Crystal |
| Case Material | Stainless Steel | Stainless Steel |
| Origin | Casio (Japan) | Japanese Movement |
Category-by-Category Analysis
Design & Aesthetics
Casio's design language vs Seiko's approach
The Casio MTP-S120L Solar Field features a Stainless Steel case at 44.5mm with Mineral 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
Solar-Powered Quartz vs Automatic Caliber 4R35
The MTP-S120L Solar Field runs the Solar-Powered Quartz (Casio Tough Solar Quartz, Months on a full solar charge; no battery replacement power reserve) at standard 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). The Prospex Samurai SRPF03 offers a longer power reserve.
Wearability & Fit
44.5mm vs 43.8mm — different wrist presence
At 44.5mm, the MTP-S120L Solar Field has a bolder wrist presence compared to the Prospex Samurai SRPF03 at 43.8mm. Water resistance differs: 100m (10 ATM) vs 200m (20 ATM).
Value & Cost of Ownership
Casio sits in the lower tier
The Casio MTP-S120L Solar Field sits at $100–$150 and the Seiko Prospex Samurai SRPF03 at $250–$500. On the specs that outlast any price: the MTP-S120L Solar Field uses Mineral Crystal with Months on a full solar charge; no battery replacement, against Hardlex Crystal and 41 Hours on the Prospex Samurai SRPF03. Service intervals are typically 5-7 years for both.
Water Resistance
100m (10 ATM) vs 200m (20 ATM)
The MTP-S120L Solar Field is rated to 100m (10 ATM) while the Prospex Samurai SRPF03 handles 200m (20 ATM). The Prospex Samurai SRPF03 offers superior water resistance.
Our Verdict
Casio
MTP-S120L Solar Field
Choose the Casio MTP-S120L Solar Field if you prioritize Casio Tough Solar Quartz engineering, Casio (Japan) craftsmanship, and 100m (10 ATM) water resistance. At $100–$150, it delivers Solar-Powered Quartz with Months on a full solar charge; no battery replacement 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 Casio MTP-S120L Solar Field and Seiko Prospex Samurai SRPF03 represent two distinct approaches to fine watchmaking — the Casio bringing Casio (Japan) tradition while Seiko delivers Japanese Movement engineering.
Frequently Asked Questions
More Comparisons
Tag Heuer Carrera Chronograph vs Casio MTP-S120L Solar Field
Tag Heuer's chronograph meets Casio's field watch
Tag Heuer Carrera Chronograph vs Seiko Prospex Samurai SRPF03
Tag Heuer's chronograph meets Seiko's diver
Tissot PRX Powermatic 80 vs Casio MTP-S120L Solar Field
Tissot's timepiece meets Casio's field watch
Explore These Watches
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.