Seiko Cal. 6639 - 904

The Seiko 6639-904 represents an important milestone in Seiko's 1977 lineup. Powered by the 6639 caliber with 30j jewels beating at 28,800 bph, it delivers a 57 hours power reserve. [seikata-wm-5717d30df2d0]

Also known as: Tuna, World Timer

Specifications

Movement

Hand-Winding

Case Material

Titanium

Case Width

45mm

Case Thickness

14.7mm

Lug Width

19mm

Crystal

Sapphire

Bezel

Inner Rotating

Water Resistance

90m

Dial Color

Blue Sunburst

Jewels

30j

Frequency

28,800 bph

Power Reserve

57 hours

Year

1977

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