Seiko Cal. 5631 - 720

The 5631-720 is a sought-after Spring Drive piece from Seiko's golden era. It features a Navy dial protected by a Hardlex crystal and offers 110m of water resistance. [seikata-wm-ac8140a49942]

Also known as: Samurai, Bullhead

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

36mm

Case Thickness

12.7mm

Lug Width

18mm

Crystal

Hardlex

Bezel

Inner Rotating

Water Resistance

110m

Dial Color

Navy

Jewels

32j

Frequency

28,800 bph

Power Reserve

49 hours

Year

1979

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