Seiko Cal. 6640 - 728

The Seiko 6640-728 represents an important milestone in Seiko's 1979 lineup. Powered by the 6640 caliber with 17j jewels beating at 21,600 bph, it delivers a 68 hours power reserve. [seikata-wm-7ca7785f11ce]

Also known as: Crown

Specifications

Movement

Hand-Winding

Case Material

Two-Tone

Case Width

34mm

Case Thickness

10.6mm

Lug Width

19mm

Crystal

Sapphire

Bezel

Coin-Edge

Water Resistance

60m

Dial Color

Black

Jewels

17j

Frequency

21,600 bph

Power Reserve

68 hours

Year

1979

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