Seiko Cal. 6638 - 631

The Seiko 6638-631 represents an important milestone in Seiko's 1971 lineup. Powered by the 6638 caliber with 24j jewels beating at 21,600 bph, it delivers a 50 hours power reserve. [seikata-wm-7e797d9fd5f8]

Also known as: Crown

Specifications

Movement

Hand-Winding

Case Material

Titanium

Case Width

41mm

Case Thickness

14.6mm

Lug Width

19mm

Crystal

Hardlex

Bezel

Fixed

Water Resistance

110m

Dial Color

Green

Jewels

24j

Frequency

21,600 bph

Power Reserve

50 hours

Year

1971

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