Seiko Cal. 6639 - 618

This Hand-Winding model from 1971 features a 37mm PVD Black case. Powered by the 6639 caliber with 18j jewels beating at 21,600 bph, it delivers a 70 hours power reserve. [seikata-wm-21184a9c187e]

Also known as: Bullhead, World Timer

Specifications

Movement

Hand-Winding

Case Material

PVD Black

Case Width

37mm

Case Thickness

9.0mm

Lug Width

18mm

Crystal

Acrylic

Bezel

Inner Rotating

Water Resistance

60m

Dial Color

Green

Jewels

18j

Frequency

21,600 bph

Power Reserve

70 hours

Year

1971

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