Seiko Cal. 5638 - 931

The Seiko 5638-931 represents an important milestone in Seiko's 1972 lineup. Powered by the 5638 caliber with 21j jewels beating at 21,600 bph, it delivers a 37 hours power reserve. [seikata-wm-76ccc253f2c8]

Also known as: Tuna, Navigator

Specifications

Movement

Spring Drive

Case Material

Stainless Steel

Case Width

46mm

Case Thickness

13.7mm

Lug Width

21mm

Crystal

Sapphire

Bezel

Rotating

Water Resistance

40m

Dial Color

Cream

Jewels

21j

Frequency

21,600 bph

Power Reserve

37 hours

Year

1972

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