Seiko Cal. 6631 - 931

The 6631-931 is a sought-after Spring Drive piece from Seiko's golden era. Powered by the 6631 caliber with 24j jewels beating at 28,800 bph, it delivers a 69 hours power reserve. [seikata-wm-50ae68b9e4b2]

Also known as: Tuna, World Timer

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

40mm

Case Thickness

13.3mm

Lug Width

21mm

Crystal

Acrylic

Bezel

Inner Rotating

Water Resistance

50m

Dial Color

Burgundy

Jewels

24j

Frequency

28,800 bph

Power Reserve

69 hours

Year

1992

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