Seiko Cal. 5661 - 639

The Seiko 5661-639 represents an important milestone in Seiko's 1969 lineup. It features a Blue Sunburst dial protected by a Acrylic crystal and offers 110m of water resistance. [seikata-wm-f90bf4ebc120]

Also known as: Monster, Helmet

Specifications

Movement

Spring Drive

Case Material

Hardlex-Coated Steel

Case Width

41mm

Case Thickness

8.6mm

Lug Width

22mm

Crystal

Acrylic

Bezel

Bidirectional

Water Resistance

110m

Dial Color

Blue Sunburst

Jewels

24j

Frequency

36,000 bph

Power Reserve

52 hours

Year

1969

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