Seiko Cal. 6631 - 405

This Spring Drive model from 1975 features a 39mm Hardlex-Coated Steel case. Powered by the 6631 caliber with 33j jewels beating at 28,800 bph, it delivers a 69 hours power reserve. [seikata-wm-32af5f120647]

Also known as: Monster, Emperor

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

39mm

Case Thickness

13.4mm

Lug Width

18mm

Crystal

Acrylic

Bezel

Bidirectional

Water Resistance

120m

Dial Color

Burgundy

Jewels

33j

Frequency

28,800 bph

Power Reserve

69 hours

Year

1975

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