Seiko Cal. 6640 - 428

The 6640-428 is a sought-after Spring Drive piece from Seiko's golden era. Powered by the 6640 caliber with 20j jewels beating at 36,000 bph, it delivers a 64 hours power reserve. [seikata-wm-d7b85efa43f7]

Also known as: Turtle, Silverwave

Specifications

Movement

Spring Drive

Case Material

Stainless Steel

Case Width

38mm

Case Thickness

9.5mm

Lug Width

19mm

Crystal

Mineral

Bezel

Coin-Edge

Water Resistance

100m

Dial Color

Cream

Jewels

20j

Frequency

36,000 bph

Power Reserve

64 hours

Year

1997

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