Seiko Cal. 5661 - 731

The Seiko 5661-731 represents an important milestone in Seiko's 1970 lineup. Powered by the 5661 caliber with 22j jewels beating at 36,000 bph, it delivers a 71 hours power reserve. [seikata-wm-14724b5dbc5b]

Also known as: Helmet

Specifications

Movement

Hand-Winding

Case Material

Gold-Plated

Case Width

36mm

Case Thickness

11.2mm

Lug Width

18mm

Crystal

Sapphire

Bezel

Inner Rotating

Water Resistance

180m

Dial Color

Blue Sunburst

Jewels

22j

Frequency

36,000 bph

Power Reserve

71 hours

Year

1970

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