Seiko Cal. 5631 - 938

The Seiko 5631-938 represents an important milestone in Seiko's 1965 lineup. Powered by the 5631 caliber with 36j jewels beating at 28,800 bph, it delivers a 69 hours power reserve. [seikata-wm-40b1866b5a4c]

Also known as: Monster, Crown

Specifications

Movement

Hand-Winding

Case Material

Titanium

Case Width

45mm

Case Thickness

13.5mm

Lug Width

18mm

Crystal

Hardlex

Bezel

Fixed

Water Resistance

30m

Dial Color

Cream

Jewels

36j

Frequency

28,800 bph

Power Reserve

69 hours

Year

1965

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