Seiko Cal. 6640 - 623

This Spring Drive model from 1985 features a 40mm Hardlex-Coated Steel case. It features a Navy dial protected by a Acrylic crystal and offers 140m of water resistance. [seikata-wm-ba4ed87f8653]

Also known as: Sumo

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

40mm

Case Thickness

15.1mm

Lug Width

18mm

Crystal

Acrylic

Bezel

Bidirectional

Water Resistance

140m

Dial Color

Navy

Jewels

21j

Frequency

28,800 bph

Power Reserve

37 hours

Year

1985

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