Seiko Cal. 6640 - 556

This Spring Drive model from 1969 features a 42mm PVD Black case. With its 20mm lug width and 9.4mm profile, it sits comfortably on most wrists. [seikata-wm-433175092c3d]

Also known as: Tuna, Bellmatic

Specifications

Movement

Spring Drive

Case Material

PVD Black

Case Width

42mm

Case Thickness

9.4mm

Lug Width

20mm

Crystal

Hardlex

Bezel

Coin-Edge

Water Resistance

200m

Dial Color

Green

Jewels

22j

Frequency

21,600 bph

Power Reserve

61 hours

Year

1969

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