Seiko Cal. 5640 - 256

The Seiko 5640-256 represents an important milestone in Seiko's 1966 lineup. With its 19mm lug width and 8.4mm profile, it sits comfortably on most wrists. [seikata-wm-3b73b5d1c514]

Also known as: Bullhead

Specifications

Movement

Hand-Winding

Case Material

Stainless Steel

Case Width

38mm

Case Thickness

8.4mm

Lug Width

19mm

Crystal

Mineral

Bezel

Inner Rotating

Water Resistance

180m

Dial Color

White

Jewels

33j

Frequency

28,800 bph

Power Reserve

64 hours

Year

1966

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