Updated
Casio MTP-S120L Solar Field vs Casio G-Shock GA-B2100 CasiOak
Casio's field watch meets Casio's diver
Quick Verdict
The Casio MTP-S120L Solar Field ($100–$150) and Casio G-Shock GA-B2100 CasiOak ($100–$150) are closely matched timepieces at similar price points. The MTP-S120L Solar Field emphasizes Casio Tough Solar Quartz engineering while the G-Shock GA-B2100 CasiOak focuses on Made in Japan craftsmanship.
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Specifications Compared
| Feature | Casio MTP-S120L Solar Field | Casio G-Shock GA-B2100 CasiOak |
|---|---|---|
| Price | $100–$150 | $100–$150 |
| Case Size | 42mm (49 x 42 x 10.9mm) | 45.4mm (48.5mm lug-to-lug, 11.9mm thick) |
| Movement | Solar-Powered Quartz | Quartz Module 5689 (Tough Solar + Bluetooth) |
| Caliber Type | Casio Tough Solar Quartz | Casio Quartz (Solar-Powered) |
| Power Reserve | Months on a full solar charge; no battery replacement | About 7 months on a full charge without light; about 18 months in power-saving (Casio) |
| Water Resistance | 100m (10 ATM) | 200m (20 ATM) |
| Crystal | Mineral Crystal | Mineral Glass |
| Case Material | Stainless Steel | Carbon Core Guard Resin |
| Origin | Casio (Japan) | Made in Japan |
Category-by-Category Analysis
Design & Aesthetics
Casio's design language vs Casio's approach
The Casio MTP-S120L Solar Field features a Stainless Steel case at 42mm (49 x 42 x 10.9mm) with Mineral Crystal protection. The Casio G-Shock GA-B2100 CasiOak offers Carbon Core Guard Resin construction at 45.4mm (48.5mm lug-to-lug, 11.9mm thick) with Mineral Glass. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Solar-Powered Quartz vs Quartz Module 5689 (Tough Solar + Bluetooth)
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 G-Shock GA-B2100 CasiOak uses the Quartz Module 5689 (Tough Solar + Bluetooth) (Casio Quartz (Solar-Powered), About 7 months on a full charge without light; about 18 months in power-saving (Casio) reserve) at standard. The G-Shock GA-B2100 CasiOak offers a longer power reserve.
Wearability & Fit
42mm (49 x 42 x 10.9mm) vs 45.4mm (48.5mm lug-to-lug, 11.9mm thick) — different wrist presence
At 42mm (49 x 42 x 10.9mm), the MTP-S120L Solar Field wears more compactly on smaller wrists compared to the G-Shock GA-B2100 CasiOak at 45.4mm (48.5mm lug-to-lug, 11.9mm thick). Water resistance differs: 100m (10 ATM) vs 200m (20 ATM).
Value & Cost of Ownership
Same tier — different value propositions
The Casio MTP-S120L Solar Field sits at $100–$150 and the Casio G-Shock GA-B2100 CasiOak at $100–$150. 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 Mineral Glass and About 7 months on a full charge without light; about 18 months in power-saving (Casio) on the G-Shock GA-B2100 CasiOak. 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 G-Shock GA-B2100 CasiOak handles 200m (20 ATM). The G-Shock GA-B2100 CasiOak 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 AmazonCasio
G-Shock GA-B2100 CasiOak
Choose the Casio G-Shock GA-B2100 CasiOak if you value Casio Quartz (Solar-Powered) technology, Made in Japan heritage, and 45.4mm (48.5mm lug-to-lug, 11.9mm thick) proportions. At $100–$150, the Quartz Module 5689 (Tough Solar + Bluetooth) with About 7 months on a full charge without light; about 18 months in power-saving (Casio) power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Casio MTP-S120L Solar Field and Casio G-Shock GA-B2100 CasiOak represent two distinct approaches to fine watchmaking — the Casio bringing Casio (Japan) tradition while Casio delivers Made in Japan engineering.
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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.