Seiko Cal. 6631 - 137

The Seiko 6631-137 represents an important milestone in Seiko's 1972 lineup. It features a Blue Sunburst dial protected by a Acrylic crystal and offers 190m of water resistance. [seikata-wm-b1fbbcbc2add]

Also known as: Helmet, Bellmatic

Specifications

Movement

Automatic

Case Material

Two-Tone

Case Width

41mm

Case Thickness

10.1mm

Lug Width

18mm

Crystal

Acrylic

Bezel

Rotating

Water Resistance

190m

Dial Color

Blue Sunburst

Jewels

36j

Frequency

36,000 bph

Power Reserve

70 hours

Year

1972

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