Seiko Cal. 6640 - 428

Seiko 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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