Seiko Cal. 5666 - 631

The Seiko 5666-631 represents an important milestone in Seiko's 1970 lineup. Powered by the 5666 caliber with 24j jewels beating at 36,000 bph, it delivers a 57 hours power reserve. [seikata-wm-e00bd29b015e]

Also known as: Helmet, Sportsmatic

Specifications

Movement

Automatic

Case Material

PVD Black

Case Width

38mm

Case Thickness

13.3mm

Lug Width

18mm

Crystal

Hardlex

Bezel

Inner Rotating

Water Resistance

30m

Dial Color

Blue Sunburst

Jewels

24j

Frequency

36,000 bph

Power Reserve

57 hours

Year

1970

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