Seiko Cal. 5640 - 337

This Hand-Winding model from 1966 features a 40mm Two-Tone case. With its 20mm lug width and 13.0mm profile, it sits comfortably on most wrists. [seikata-wm-c3712e2d651b]

Also known as: Sumo

Specifications

Movement

Hand-Winding

Case Material

Two-Tone

Case Width

40mm

Case Thickness

13.0mm

Lug Width

20mm

Crystal

Mineral

Bezel

Inner Rotating

Water Resistance

150m

Dial Color

Blue Sunburst

Jewels

23j

Frequency

28,800 bph

Power Reserve

61 hours

Year

1966

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