Seiko Cal. 6640 - 278

This Spring Drive model from 1974 features a 46mm Hardlex-Coated Steel case. Powered by the 6640 caliber with 18j jewels beating at 36,000 bph, it delivers a 55 hours power reserve. [seikata-wm-58d78d981607]

Also known as: Bullhead

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

46mm

Case Thickness

14.0mm

Lug Width

19mm

Crystal

Mineral

Bezel

Rotating

Water Resistance

200m

Dial Color

Blue Sunburst

Jewels

18j

Frequency

36,000 bph

Power Reserve

55 hours

Year

1974

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