Seiko Cal. 6637 - 831

Released in 1977, the Cal. 6637 with design code 831 was part of Seiko's domestic market collection. Powered by the 6637 caliber with 27j jewels beating at 21,600 bph, it delivers a 45 hours power reserve. [seikata-wm-55fa89dab344]

Also known as: Bullhead, World Timer

Specifications

Movement

Automatic

Case Material

Gold-Plated

Case Width

35mm

Case Thickness

13.7mm

Lug Width

19mm

Crystal

Sapphire

Bezel

Inner Rotating

Water Resistance

30m

Dial Color

Champagne

Jewels

27j

Frequency

21,600 bph

Power Reserve

45 hours

Year

1977

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