Head-to-Head Comparison

Updated September 5, 2026

Casio G-Shock GA-B2100 CasiOak vs Hamilton Khaki Aviation Pilot Auto

Casio's diver meets Hamilton's pilot watch

Quick Verdict

The Casio G-Shock GA-B2100 CasiOak ($100–$150) offers Casio Quartz (Solar-Powered) precision in the tier below the Hamilton Khaki Aviation Pilot Auto ($1,000–$1,500). The G-Shock GA-B2100 CasiOak measures 45.4mm (48.5mm lug-to-lug, 11.9mm thick) and is rated 200m (20 ATM). The Khaki Aviation Pilot Auto 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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Hamilton

Khaki Aviation Pilot Auto

$1,000–$1,500

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Specifications Compared

Feature	Casio G-Shock GA-B2100 CasiOak	Hamilton Khaki Aviation Pilot Auto
Price	$100–$150	$1,000–$1,500
Case Size	45.4mm (48.5mm lug-to-lug, 11.9mm thick)	38mm
Movement	Quartz Module 5689 (Tough Solar + Bluetooth)	Automatic H-10 (ETA 2824-2 base)
Caliber Type	Casio Quartz (Solar-Powered)	Hamilton/ETA 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

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Design & Aesthetics

Edge: Draw

Casio's design language vs Hamilton'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 Hamilton Khaki Aviation Pilot Auto offers Stainless Steel construction at 38mm with Sapphire Crystal. Both represent their brand's distinct design philosophy and heritage.

⚙️

Movement & Performance

Edge: Hamilton

Quartz Module 5689 (Tough Solar + Bluetooth) vs Automatic H-10 (ETA 2824-2 base)

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 Khaki Aviation Pilot Auto uses the Automatic H-10 (ETA 2824-2 base) (Hamilton/ETA Automatic, 80 Hours reserve) at 21,600 vph (3 Hz). The Khaki Aviation Pilot Auto offers a longer power reserve.

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Wearability & Fit

Edge: Hamilton

45.4mm (48.5mm lug-to-lug, 11.9mm thick) vs 38mm — 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 Khaki Aviation Pilot Auto at 38mm. 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 Hamilton Khaki Aviation Pilot Auto at $1,000–$1,500. 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 Khaki Aviation Pilot Auto. Service intervals are typically 5-7 years for both.

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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 Khaki Aviation Pilot Auto 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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Hamilton

Khaki Aviation Pilot Auto

Choose the Hamilton Khaki Aviation Pilot Auto if you value Hamilton/ETA Automatic technology, Swiss Made heritage, and 38mm proportions. At $1,000–$1,500, the Automatic H-10 (ETA 2824-2 base) 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 Hamilton Khaki Aviation Pilot Auto represent two distinct approaches to fine watchmaking — the Casio bringing Made in Japan tradition while Hamilton delivers Swiss Made engineering.

Frequently Asked Questions

The Hamilton Khaki Aviation Pilot Auto 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 $1,000–$1,500), 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 Hamilton Khaki Aviation Pilot Auto 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 Khaki Aviation Pilot Auto at 38mm with 100m (10 ATM) is similarly capable. The G-Shock GA-B2100 CasiOak uses Mineral Glass while the Khaki Aviation Pilot Auto 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.