Seiko Cal. 6640 - 987

The Seiko 6640-987 represents an important milestone in Seiko's 1978 lineup. It features a Silver dial protected by a Mineral crystal and offers 180m of water resistance. [seikata-wm-1f67be5f82fe]

Also known as: Tuna

Specifications

Movement

Automatic

Case Material

PVD Black

Case Width

46mm

Case Thickness

9.6mm

Lug Width

18mm

Crystal

Mineral

Bezel

Fixed

Water Resistance

180m

Dial Color

Silver

Jewels

32j

Frequency

28,800 bph

Power Reserve

42 hours

Year

1978

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