Seiko Cal. 6640 - 393

The 6640-393 is a sought-after Solar piece from Seiko's golden era. Powered by the 6640 caliber with 20j jewels beating at 36,000 bph, it delivers a 63 hours power reserve. [seikata-wm-2f17e75e344c]

Also known as: Sumo, Flighty

Specifications

Movement

Solar

Case Material

PVD Black

Case Width

43mm

Case Thickness

12.3mm

Lug Width

18mm

Crystal

Acrylic

Bezel

Bidirectional

Water Resistance

110m

Dial Color

Blue Sunburst

Jewels

20j

Frequency

36,000 bph

Power Reserve

63 hours

Year

1971

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