Seiko Cal. 6640 - 864

The 6640-864 is a sought-after Spring Drive piece from Seiko's golden era. Powered by the 6640 caliber with 36j jewels beating at 28,800 bph, it delivers a 70 hours power reserve. [seikata-wm-79c24e677b01]

Also known as: Tuna, Bullhead

Specifications

Movement

Spring Drive

Case Material

Stainless Steel

Case Width

44mm

Case Thickness

10.3mm

Lug Width

21mm

Crystal

Acrylic

Bezel

Inner Rotating

Water Resistance

110m

Dial Color

Navy

Jewels

36j

Frequency

28,800 bph

Power Reserve

70 hours

Year

1975

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