Seiko Cal. 6640 - 650

The 6640-650 is a sought-after Spring Drive piece from Seiko's golden era. Powered by the 6640 caliber with 28j jewels beating at 21,600 bph, it delivers a 71 hours power reserve. [seikata-wm-d3e9d15e7e44]

Also known as: Tuna, UFO

Specifications

Movement

Spring Drive

Case Material

Stainless Steel

Case Width

39mm

Case Thickness

14.0mm

Lug Width

18mm

Crystal

Mineral

Bezel

Bidirectional

Water Resistance

60m

Dial Color

Cream

Jewels

28j

Frequency

21,600 bph

Power Reserve

71 hours

Year

1989

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