Seiko Cal. 6640 - 411

This Spring Drive model from 1974 features a 38mm Stainless Steel case. It features a Blue Sunburst dial protected by a Sapphire crystal and offers 40m of water resistance. [seikata-wm-f4012a78c150]

Also known as: Tuna

Specifications

Movement

Spring Drive

Case Material

Stainless Steel

Case Width

38mm

Case Thickness

15.6mm

Lug Width

18mm

Crystal

Sapphire

Bezel

Coin-Edge

Water Resistance

40m

Dial Color

Blue Sunburst

Jewels

22j

Frequency

36,000 bph

Power Reserve

55 hours

Year

1974

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