Seiko Cal. 6640 - 555

The Seiko 6640-555 represents an important milestone in Seiko's 1975 lineup. Powered by the 6640 caliber with 28j jewels beating at 28,800 bph, it delivers a 38 hours power reserve. [seikata-wm-806116e1082e]

Also known as: Monster, Emperor

Specifications

Movement

Automatic

Case Material

Hardlex-Coated Steel

Case Width

40mm

Case Thickness

8.6mm

Lug Width

20mm

Crystal

Acrylic

Bezel

Coin-Edge

Water Resistance

120m

Dial Color

Black

Jewels

28j

Frequency

28,800 bph

Power Reserve

38 hours

Year

1975

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