Seiko Cal. 5640 - 421

This Spring Drive model from 1977 features a 38mm PVD Black case. With its 22mm lug width and 14.3mm profile, it sits comfortably on most wrists. [seikata-wm-3521b2ad63f7]

Also known as: Monster, Sportsmatic

Specifications

Movement

Spring Drive

Case Material

PVD Black

Case Width

38mm

Case Thickness

14.3mm

Lug Width

22mm

Crystal

Sapphire

Bezel

Coin-Edge

Water Resistance

160m

Dial Color

Navy

Jewels

20j

Frequency

28,800 bph

Power Reserve

68 hours

Year

1977

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