Seiko Cal. 6640 - 957

The 6640-957 is a sought-after Spring Drive piece from Seiko's golden era. Powered by the 6640 caliber with 27j jewels beating at 21,600 bph, it delivers a 40 hours power reserve. [seikata-wm-9b16b499a6ff]

Also known as: Turtle, Crown

Specifications

Movement

Spring Drive

Case Material

Gold-Plated

Case Width

39mm

Case Thickness

15.4mm

Lug Width

22mm

Crystal

Hardlex

Bezel

Bidirectional

Water Resistance

50m

Dial Color

Silver

Jewels

27j

Frequency

21,600 bph

Power Reserve

40 hours

Year

1983

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