Seiko Cal. 6638 - 231

Released in 1978, the Cal. 6638 with design code 231 was part of Seiko's domestic market collection. It features a Black dial protected by a Sapphire crystal and offers 50m of water resistance. [seikata-wm-2478957d6b40]

Also known as: Tuna, Flighty

Specifications

Movement

Automatic

Case Material

Two-Tone

Case Width

44mm

Case Thickness

12.9mm

Lug Width

21mm

Crystal

Sapphire

Bezel

Inner Rotating

Water Resistance

50m

Dial Color

Black

Jewels

18j

Frequency

28,800 bph

Power Reserve

57 hours

Year

1978

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