Seiko Cal. 5645 - 640

The 5645-640 is a sought-after Spring Drive piece from Seiko's golden era. Powered by the 5645 caliber with 32j jewels beating at 28,800 bph, it delivers a 39 hours power reserve. [seikata-wm-663249beaee6]

Also known as: Tuna, Baby Tuna

Specifications

Movement

Spring Drive

Case Material

Gold-Plated

Case Width

37mm

Case Thickness

9.4mm

Lug Width

21mm

Crystal

Acrylic

Bezel

Fixed

Water Resistance

90m

Dial Color

White

Jewels

32j

Frequency

28,800 bph

Power Reserve

39 hours

Year

1971

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