Seiko Cal. 6331 - 920

This Spring Drive model from 1966 features a 40mm Titanium case. Powered by the 6331 caliber with 26j jewels beating at 28,800 bph, it delivers a 55 hours power reserve. [seikata-wm-120ec6cb2164]

Also known as: Bullhead, Helmet

Specifications

Movement

Spring Drive

Case Material

Titanium

Case Width

40mm

Case Thickness

14.7mm

Lug Width

22mm

Crystal

Acrylic

Bezel

Bidirectional

Water Resistance

80m

Dial Color

Green

Jewels

26j

Frequency

28,800 bph

Power Reserve

55 hours

Year

1966

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