Casio Pro Trek PRG270-1 vs Casio G-Shock GA-B2100 CasiOak
Casio's timepiece meets Casio's diver
Quick Verdict
The Casio G-Shock GA-B2100 CasiOak ($100–$150) delivers Casio Quartz (Solar-Powered) technology in the tier below the Casio Pro Trek PRG270-1 ($150–$250). The G-Shock GA-B2100 CasiOak measures 45.4mm (48.5mm lug-to-lug, 11.9mm thick) and is rated 200m (20 ATM). The Pro Trek PRG270-1 justifies its premium with Casio (Japan) heritage and Tough Solar (Solar Quartz). Both represent excellent choices in the luxury watch category.
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Specifications Compared
| Feature | Casio Pro Trek PRG270-1 | Casio G-Shock GA-B2100 CasiOak |
|---|---|---|
| Price | $150–$250 | $100–$150 |
| Case Size | 54.6 × 52.4 × 15mm | 45.4mm (48.5mm lug-to-lug, 11.9mm thick) |
| Movement | Tough Solar (Solar Quartz) | Quartz Module 5689 (Tough Solar + Bluetooth) |
| Caliber Type | Tough Solar Quartz (No Battery Change) | Casio Quartz (Solar-Powered) |
| Power Reserve | Tough Solar (Rechargeable) | 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 Glass | Mineral Glass |
| Case Material | Resin | 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 Pro Trek PRG270-1 features a Resin case at 54.6 × 52.4 × 15mm with Mineral Glass 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
Tough Solar (Solar Quartz) vs Quartz Module 5689 (Tough Solar + Bluetooth)
The Pro Trek PRG270-1 runs the Tough Solar (Solar Quartz) (Tough Solar Quartz (No Battery Change), Tough Solar (Rechargeable) 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
54.6 × 52.4 × 15mm vs 45.4mm (48.5mm lug-to-lug, 11.9mm thick) — different wrist presence
At 54.6 × 52.4 × 15mm, the Pro Trek PRG270-1 has a bolder wrist presence 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
Casio sits in the lower tier
The Casio Pro Trek PRG270-1 sits at $150–$250 and the Casio G-Shock GA-B2100 CasiOak at $100–$150. On the specs that outlast any price: the Pro Trek PRG270-1 uses Mineral Glass with Tough Solar (Rechargeable), 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 Pro Trek PRG270-1 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
Pro Trek PRG270-1
Choose the Casio Pro Trek PRG270-1 if you prioritize Tough Solar Quartz (No Battery Change) engineering, Casio (Japan) craftsmanship, and 100m (10 ATM) water resistance. At $150–$250, it delivers Tough Solar (Solar Quartz) with Tough Solar (Rechargeable) 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 Pro Trek PRG270-1 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.