Seiko Cal. 6631 - 131

The 6631-131 is a sought-after Spring Drive piece from Seiko's golden era. With its 22mm lug width and 13.8mm profile, it sits comfortably on most wrists. [seikata-wm-574790b7c3ad]

Also known as: UFO, Baby Tuna

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

43mm

Case Thickness

13.8mm

Lug Width

22mm

Crystal

Hardlex

Bezel

Bidirectional

Water Resistance

140m

Dial Color

Cream

Jewels

23j

Frequency

21,600 bph

Power Reserve

71 hours

Year

1979

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