Seiko Cal. 6640 - 746

This Spring Drive model from 1968 features a 34mm Hardlex-Coated Steel case. Powered by the 6640 caliber with 26j jewels beating at 28,800 bph, it delivers a 38 hours power reserve. [seikata-wm-630cba0d92d6]

Also known as: Bullhead, Crown

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

34mm

Case Thickness

9.8mm

Lug Width

20mm

Crystal

Mineral

Bezel

Inner Rotating

Water Resistance

180m

Dial Color

Silver

Jewels

26j

Frequency

28,800 bph

Power Reserve

38 hours

Year

1968

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