Seiko Cal. 5631 - 157

Released in 1971, the Cal. 5631 with design code 157 was part of Seiko's domestic market collection. The Coin-Edge bezel and 38mm case give it a distinctive presence on the wrist. [seikata-wm-f47a5fba39ba]

Also known as: Monster, Baby Tuna

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

38mm

Case Thickness

8.0mm

Lug Width

21mm

Crystal

Mineral

Bezel

Coin-Edge

Water Resistance

30m

Dial Color

Black

Jewels

21j

Frequency

28,800 bph

Power Reserve

60 hours

Year

1971

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