Seiko Cal. 5631 - 637

Released in 1970, the Cal. 5631 with design code 637 was part of Seiko's domestic market collection. It features a Green dial protected by a Sapphire crystal and offers 60m of water resistance. [seikata-wm-7e917d6e48e7]

Also known as: Baby Tuna, Emperor

Specifications

Movement

Spring Drive

Case Material

Gold-Plated

Case Width

39mm

Case Thickness

11.3mm

Lug Width

22mm

Crystal

Sapphire

Bezel

Bidirectional

Water Resistance

60m

Dial Color

Green

Jewels

27j

Frequency

36,000 bph

Power Reserve

48 hours

Year

1970

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