Seiko Cal. 6631 - 840

Released in 1976, the Cal. 6631 with design code 840 was part of Seiko's domestic market collection. It features a Navy dial protected by a Mineral crystal and offers 150m of water resistance. [seikata-wm-d5e8675853ca]

Also known as: Baby Tuna

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

37mm

Case Thickness

15.8mm

Lug Width

21mm

Crystal

Mineral

Bezel

Inner Rotating

Water Resistance

150m

Dial Color

Navy

Jewels

24j

Frequency

36,000 bph

Power Reserve

49 hours

Year

1976

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