Seiko Cal. 6640 - 631

Released in 1997, the Cal. 6640 with design code 631 was part of Seiko's domestic market collection. The Bidirectional bezel and 45mm case give it a distinctive presence on the wrist. [seikata-wm-d8dcf8cbf7c5]

Also known as: UFO, Navigator

Specifications

Movement

Hand-Winding

Case Material

Gold-Plated

Case Width

45mm

Case Thickness

11.8mm

Lug Width

22mm

Crystal

Mineral

Bezel

Bidirectional

Water Resistance

190m

Dial Color

White

Jewels

30j

Frequency

21,600 bph

Power Reserve

63 hours

Year

1997

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