Seiko Cal. 5640 - 731

The 5640-731 is a sought-after Hand-Winding piece from Seiko's golden era. Powered by the 5640 caliber with 17j jewels beating at 28,800 bph, it delivers a 45 hours power reserve. [seikata-wm-98824ee9daa0]

Also known as: Turtle, Monster

Specifications

Movement

Hand-Winding

Case Material

Gold-Plated

Case Width

41mm

Case Thickness

13.8mm

Lug Width

18mm

Crystal

Hardlex

Bezel

Bidirectional

Water Resistance

190m

Dial Color

Cream

Jewels

17j

Frequency

28,800 bph

Power Reserve

45 hours

Year

1979

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