Seiko Cal. 5631 - 840

The Seiko 5631-840 represents an important milestone in Seiko's 1973 lineup. Powered by the 5631 caliber with 31j jewels beating at 28,800 bph, it delivers a 58 hours power reserve. [seikata-wm-e34675b3ea9e]

Also known as: Sumo, Pogue

Specifications

Movement

Hand-Winding

Case Material

PVD Black

Case Width

34mm

Case Thickness

8.8mm

Lug Width

18mm

Crystal

Acrylic

Bezel

Rotating

Water Resistance

60m

Dial Color

Champagne

Jewels

31j

Frequency

28,800 bph

Power Reserve

58 hours

Year

1973

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