Seiko Cal. 6640 - 538

The Seiko 6640-538 represents an important milestone in Seiko's 1994 lineup. The Inner Rotating bezel and 41mm case give it a distinctive presence on the wrist. [seikata-wm-10f2cb2f4325]

Also known as: Helmet, Sportsmatic

Specifications

Movement

Automatic

Case Material

Titanium

Case Width

41mm

Case Thickness

15.9mm

Lug Width

19mm

Crystal

Sapphire

Bezel

Inner Rotating

Water Resistance

60m

Dial Color

Cream

Jewels

30j

Frequency

36,000 bph

Power Reserve

37 hours

Year

1994

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