Seiko Cal. 6631 - 840

The 6631-840 is a sought-after Spring Drive piece from Seiko's golden era. With its 21mm lug width and 8.9mm profile, it sits comfortably on most wrists. [seikata-wm-60d9b7176041]

Also known as: UFO

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

43mm

Case Thickness

8.9mm

Lug Width

21mm

Crystal

Hardlex

Bezel

Rotating

Water Resistance

160m

Dial Color

White

Jewels

19j

Frequency

36,000 bph

Power Reserve

44 hours

Year

1981

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