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Seiko Alpinist SPB121 vs Hamilton Khaki Field Mechanical

Both are field / explorer watches in the upper tier — here's how the specs differ and which to pick.

Last verified 2026-06-11 · specs from manufacturer data · tier = price band, confirm the live price at the retailer

SpecSeiko Alpinist SPB121Hamilton Khaki Field Mechanical
MovementAutomaticHand-wound
Water resistance200m50m
Case size39.5mm38mm
Crystalsapphiresapphire
StyleField / explorerField / explorer
Price tierUpperUpper

Which should you buy?

Where to buy

Check the Seiko Alpinist SPB121 price on Amazon →

Check the Hamilton Khaki Field Mechanical price on Amazon →

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FAQ

What's the difference between the Seiko Alpinist SPB121 and the Hamilton Khaki Field Mechanical?
Both are field / explorer watches in the upper tier. The Seiko Alpinist SPB121 is automatic, 200m water resistance, 39.5mm, sapphire crystal; the Hamilton Khaki Field Mechanical is hand-wound, 50m water resistance, 38mm, sapphire crystal.

Which has better water resistance, the Seiko Alpinist SPB121 or the Hamilton Khaki Field Mechanical?
The Seiko Alpinist SPB121, rated 200m, versus 50m on the other. Pick 100m or higher for swimming and 200m+ for diving.

Which is better value, the Seiko Alpinist SPB121 or the Hamilton Khaki Field Mechanical?
Both sit in the upper tier, so it comes down to movement, water resistance and case size — see the spec table above.

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