Seiko Cal. 6640 - 926

The 6640-926 is a sought-after Automatic piece from Seiko's golden era. Powered by the 6640 caliber with 23j jewels beating at 28,800 bph, it delivers a 60 hours power reserve. [seikata-wm-08d24dff7148]

Also known as: Monster, Sumo

Specifications

Movement

Automatic

Case Material

Hardlex-Coated Steel

Case Width

43mm

Case Thickness

14.1mm

Lug Width

19mm

Crystal

Acrylic

Bezel

Coin-Edge

Water Resistance

60m

Dial Color

Navy

Jewels

23j

Frequency

28,800 bph

Power Reserve

60 hours

Year

1978

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