Seiko Cal. 6640 - 571

The Seiko 6640-571 represents an important milestone in Seiko's 1981 lineup. It features a Cream dial protected by a Hardlex crystal and offers 90m of water resistance. [seikata-wm-827b41602e52]

Also known as: Sumo, Sportsmatic

Specifications

Movement

Hand-Winding

Case Material

Hardlex-Coated Steel

Case Width

40mm

Case Thickness

9.7mm

Lug Width

18mm

Crystal

Hardlex

Bezel

Coin-Edge

Water Resistance

90m

Dial Color

Cream

Jewels

27j

Frequency

21,600 bph

Power Reserve

68 hours

Year

1981

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