Seiko Cal. 6631 - 631

Released in 1988, the Cal. 6631 with design code 631 was part of Seiko's domestic market collection. Powered by the 6631 caliber with 35j jewels beating at 28,800 bph, it delivers a 54 hours power reserve. [seikata-wm-1edb8daacdf7]

Also known as: Monster, UFO

Specifications

Movement

Spring Drive

Case Material

Titanium

Case Width

41mm

Case Thickness

11.9mm

Lug Width

20mm

Crystal

Hardlex

Bezel

Rotating

Water Resistance

150m

Dial Color

Green

Jewels

35j

Frequency

28,800 bph

Power Reserve

54 hours

Year

1988

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