Seiko Cal. 5631 - 581

This Hand-Winding model from 1968 features a 37mm Titanium case. It features a Burgundy dial protected by a Hardlex crystal and offers 140m of water resistance. [seikata-wm-3772b013a9f7]

Also known as: Tuna, UFO

Specifications

Movement

Hand-Winding

Case Material

Titanium

Case Width

37mm

Case Thickness

9.4mm

Lug Width

20mm

Crystal

Hardlex

Bezel

Rotating

Water Resistance

140m

Dial Color

Burgundy

Jewels

28j

Frequency

36,000 bph

Power Reserve

47 hours

Year

1968

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