Seiko Cal. 6645 - 256

The Seiko 6645-256 represents an important milestone in Seiko's 1968 lineup. It features a Blue Sunburst dial protected by a Sapphire crystal and offers 100m of water resistance. [seikata-wm-5834d14dc3ce]

Also known as: Tuna, World Timer

Specifications

Movement

Hand-Winding

Case Material

Titanium

Case Width

41mm

Case Thickness

13.7mm

Lug Width

20mm

Crystal

Sapphire

Bezel

Bidirectional

Water Resistance

100m

Dial Color

Blue Sunburst

Jewels

20j

Frequency

21,600 bph

Power Reserve

57 hours

Year

1968

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