Seiko Cal. 6643 - 660

The Seiko 6643-660 represents an important milestone in Seiko's 1967 lineup. With its 18mm lug width and 11.3mm profile, it sits comfortably on most wrists. [seikata-wm-c9a9fde69bcd]

Also known as: Sumo, Helmet

Specifications

Movement

Solar

Case Material

Gold-Plated

Case Width

44mm

Case Thickness

11.3mm

Lug Width

18mm

Crystal

Sapphire

Bezel

Inner Rotating

Water Resistance

120m

Dial Color

Silver

Jewels

35j

Frequency

21,600 bph

Power Reserve

37 hours

Year

1967

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