Seiko Cal. 6616 - 731

The Seiko 6616-731 represents an important milestone in Seiko's 1973 lineup. It features a Black dial protected by a Hardlex crystal and offers 180m of water resistance. [seikata-wm-0d4a33d460dc]

Also known as: Tuna

Specifications

Movement

Hand-Winding

Case Material

Hardlex-Coated Steel

Case Width

37mm

Case Thickness

12.7mm

Lug Width

21mm

Crystal

Hardlex

Bezel

Bidirectional

Water Resistance

180m

Dial Color

Black

Jewels

25j

Frequency

21,600 bph

Power Reserve

41 hours

Year

1973

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