Seiko Cal. 6640 - 517

The 6640-517 is a sought-after Spring Drive piece from Seiko's golden era. The Inner Rotating bezel and 37mm case give it a distinctive presence on the wrist. [seikata-wm-d20ba083f4ee]

Also known as: Sumo, Emperor

Specifications

Movement

Spring Drive

Case Material

PVD Black

Case Width

37mm

Case Thickness

14.5mm

Lug Width

18mm

Crystal

Sapphire

Bezel

Inner Rotating

Water Resistance

50m

Dial Color

Green

Jewels

28j

Frequency

28,800 bph

Power Reserve

40 hours

Year

1980

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