Seiko Cal. 6640 - 721

The Seiko 6640-721 represents an important milestone in Seiko's 1966 lineup. It features a Green dial protected by a Mineral crystal and offers 110m of water resistance. [seikata-wm-b14c3e2112dc]

Specifications

Movement

Spring Drive

Case Material

Titanium

Case Width

34mm

Case Thickness

10.4mm

Lug Width

22mm

Crystal

Mineral

Bezel

Inner Rotating

Water Resistance

110m

Dial Color

Green

Jewels

18j

Frequency

28,800 bph

Power Reserve

53 hours

Year

1966

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