Seiko Cal. 5634 - 638

The Seiko 5634-638 represents an important milestone in Seiko's 1966 lineup. Powered by the 5634 caliber with 31j jewels beating at 36,000 bph, it delivers a 55 hours power reserve. [seikata-wm-feac0ed50f1a]

Also known as: Helmet

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

42mm

Case Thickness

15.6mm

Lug Width

18mm

Crystal

Sapphire

Bezel

Bidirectional

Water Resistance

60m

Dial Color

Blue Sunburst

Jewels

31j

Frequency

36,000 bph

Power Reserve

55 hours

Year

1966

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