Seiko Cal. 6640 - 551

The Seiko 6640-551 represents an important milestone in Seiko's 1969 lineup. Powered by the 6640 caliber with 17j jewels beating at 21,600 bph, it delivers a 71 hours power reserve. [seikata-wm-48b9bbcc6ec3]

Also known as: UFO

Specifications

Movement

Spring Drive

Case Material

PVD Black

Case Width

39mm

Case Thickness

10.3mm

Lug Width

18mm

Crystal

Sapphire

Bezel

Inner Rotating

Water Resistance

160m

Dial Color

Green

Jewels

17j

Frequency

21,600 bph

Power Reserve

71 hours

Year

1969

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