Seiko Cal. 5640 - 310

The Seiko 5640-310 represents an important milestone in Seiko's 1969 lineup. With its 21mm lug width and 15.2mm profile, it sits comfortably on most wrists. [seikata-wm-e0859fd616fa]

Also known as: Bullhead

Specifications

Movement

Hand-Winding

Case Material

Gold-Plated

Case Width

43mm

Case Thickness

15.2mm

Lug Width

21mm

Crystal

Sapphire

Bezel

Bidirectional

Water Resistance

100m

Dial Color

Silver

Jewels

26j

Frequency

36,000 bph

Power Reserve

36 hours

Year

1969

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