Head-to-Head Comparison

Updated September 5, 2026

Casio G-Shock GA-B2100 CasiOak vs Tissot PRX Powermatic 80 35mm

Casio's diver meets Tissot's timepiece

Quick Verdict

The Casio G-Shock GA-B2100 CasiOak ($100–$150) offers Casio Quartz (Solar-Powered) precision in the tier below the Tissot PRX Powermatic 80 35mm ($500–$1,000). The G-Shock GA-B2100 CasiOak measures 45.4mm (48.5mm lug-to-lug, 11.9mm thick) and is rated 200m (20 ATM). The PRX Powermatic 80 35mm counters with Swiss Made craftsmanship and 100m (10 ATM) water resistance. Both are exceptional watches for their respective tiers.

CasioG-Shock GA-B2100 CasiOak$100–$150 Check price View the dossier

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Casio

G-Shock GA-B2100 CasiOak

$100–$150

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Tissot

PRX Powermatic 80 35mm

$500–$1,000

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Specifications Compared

Feature	Casio G-Shock GA-B2100 CasiOak	Tissot PRX Powermatic 80 35mm
Price	$100–$150	$500–$1,000
Case Size	45.4mm (48.5mm lug-to-lug, 11.9mm thick)	35mm
Movement	Quartz Module 5689 (Tough Solar + Bluetooth)	Automatic Powermatic 80 (Caliber 80.111)
Caliber Type	Casio Quartz (Solar-Powered)	ETA/Tissot Automatic
Power Reserve	About 7 months on a full charge without light; about 18 months in power-saving (Casio)	80 Hours
Water Resistance	200m (20 ATM)	100m (10 ATM)
Crystal	Mineral Glass	Sapphire Crystal
Case Material	Carbon Core Guard Resin	Stainless Steel
Origin	Made in Japan	Swiss Made

Category-by-Category Analysis

🎨

Design & Aesthetics

Edge: Draw

Casio's design language vs Tissot's approach

The Casio G-Shock GA-B2100 CasiOak features a Carbon Core Guard Resin case at 45.4mm (48.5mm lug-to-lug, 11.9mm thick) with Mineral Glass protection. The Tissot PRX Powermatic 80 35mm offers Stainless Steel construction at 35mm with Sapphire Crystal. Both represent their brand's distinct design philosophy and heritage.

⚙️

Movement & Performance

Edge: Tissot

Quartz Module 5689 (Tough Solar + Bluetooth) vs Automatic Powermatic 80 (Caliber 80.111)

The G-Shock GA-B2100 CasiOak runs 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) power reserve) at standard frequency. The PRX Powermatic 80 35mm uses the Automatic Powermatic 80 (Caliber 80.111) (ETA/Tissot Automatic, 80 Hours reserve) at 21,600 vph (3 Hz). The PRX Powermatic 80 35mm offers a longer power reserve.

📏

Wearability & Fit

Edge: Tissot

45.4mm (48.5mm lug-to-lug, 11.9mm thick) vs 35mm — different wrist presence

At 45.4mm (48.5mm lug-to-lug, 11.9mm thick), the G-Shock GA-B2100 CasiOak has a bolder wrist presence compared to the PRX Powermatic 80 35mm at 35mm. Water resistance differs: 200m (20 ATM) vs 100m (10 ATM).

💰

Value & Cost of Ownership

Edge: Casio

Casio sits in the lower tier

The Casio G-Shock GA-B2100 CasiOak sits at $100–$150 and the Tissot PRX Powermatic 80 35mm at $500–$1,000. On the specs that outlast any price: the G-Shock GA-B2100 CasiOak uses Mineral Glass with About 7 months on a full charge without light; about 18 months in power-saving (Casio), against Sapphire Crystal and 80 Hours on the PRX Powermatic 80 35mm. Service intervals are typically 5-7 years for both.

💧

Water Resistance

Edge: Casio

200m (20 ATM) vs 100m (10 ATM)

The G-Shock GA-B2100 CasiOak is rated to 200m (20 ATM) while the PRX Powermatic 80 35mm handles 100m (10 ATM). The G-Shock GA-B2100 CasiOak is better suited for water activities.

Our Verdict

Casio

G-Shock GA-B2100 CasiOak

Choose the Casio G-Shock GA-B2100 CasiOak if you prioritize Casio Quartz (Solar-Powered) engineering, Made in Japan craftsmanship, and 200m (20 ATM) water resistance. At $100–$150, it delivers 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.

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Tissot

PRX Powermatic 80 35mm

Choose the Tissot PRX Powermatic 80 35mm if you value ETA/Tissot Automatic technology, Swiss Made heritage, and 35mm proportions. At $500–$1,000, the Automatic Powermatic 80 (Caliber 80.111) with 80 Hours power reserve makes it a compelling choice.

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The Bottom Line

The Casio G-Shock GA-B2100 CasiOak and Tissot PRX Powermatic 80 35mm represent two distinct approaches to fine watchmaking — the Casio bringing Made in Japan tradition while Tissot delivers Swiss Made engineering.

Frequently Asked Questions

The Tissot PRX Powermatic 80 35mm is the better buy if you want a mechanical movement; the Casio G-Shock GA-B2100 CasiOak is the better buy if you want solar power and quartz accuracy with no servicing. For water, the Casio G-Shock GA-B2100 CasiOak is rated 200 m against 100 m, which is the difference between swimming and diving on one side and splashes on the other. On price, the Casio G-Shock GA-B2100 CasiOak sits a band lower ($100–$150 against $500–$1,000), so it is the cheaper way into the category. Neither is better at everything; the spec table above shows movement, case size, water resistance and crystal side by side so you can weigh what matters to you. We do not test units, so this is the makers' data, not a bench result.

The Casio G-Shock GA-B2100 CasiOak offers better upfront value, sitting a tier lower at $100–$150. However, the Tissot PRX Powermatic 80 35mm may justify its premium with superior finishing, heritage, or resale value.

Both are suitable for daily wear. The G-Shock GA-B2100 CasiOak at 45.4mm (48.5mm lug-to-lug, 11.9mm thick) with 200m (20 ATM) water resistance handles everyday situations. The PRX Powermatic 80 35mm at 35mm with 100m (10 ATM) is similarly capable. The G-Shock GA-B2100 CasiOak uses Mineral Glass while the PRX Powermatic 80 35mm uses Sapphire Crystal. Sapphire resists scratches noticeably better than mineral glass.

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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.