Seiko Cal. 6691 - 640

The 6691-640 is a sought-after Spring Drive piece from Seiko's golden era. The Coin-Edge bezel and 41mm case give it a distinctive presence on the wrist. [seikata-wm-ca03c53d028a]

Specifications

Movement

Spring Drive

Case Material

Two-Tone

Case Width

41mm

Case Thickness

13.6mm

Lug Width

21mm

Crystal

Sapphire

Bezel

Coin-Edge

Water Resistance

170m

Dial Color

Blue Sunburst

Jewels

31j

Frequency

28,800 bph

Power Reserve

51 hours

Year

1973

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