Seiko Cal. 6640 - 726

The 6640-726 is a sought-after Quartz piece from Seiko's golden era. Powered by the 6640 caliber with 28j jewels beating at 28,800 bph, it delivers a 54 hours power reserve. [seikata-wm-03e1ae9a41b7]

Also known as: Helmet, Rally

Specifications

Movement

Quartz

Case Material

PVD Black

Case Width

42mm

Case Thickness

8.6mm

Lug Width

18mm

Crystal

Acrylic

Bezel

Coin-Edge

Water Resistance

90m

Dial Color

Burgundy

Jewels

28j

Frequency

28,800 bph

Power Reserve

54 hours

Year

1981

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