Seiko Cal. 6640 - 637

The Seiko 6640-637 represents an important milestone in Seiko's 1989 lineup. The Bidirectional bezel and 40mm case give it a distinctive presence on the wrist. [seikata-wm-00a7e8cf6fa3]

Specifications

Movement

Hand-Winding

Case Material

PVD Black

Case Width

40mm

Case Thickness

14.3mm

Lug Width

19mm

Crystal

Mineral

Bezel

Bidirectional

Water Resistance

110m

Dial Color

Blue Sunburst

Jewels

17j

Frequency

21,600 bph

Power Reserve

38 hours

Year

1989

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