Seiko Cal. 6640 - 312

Released in 1978, the Cal. 6640 with design code 312 was part of Seiko's domestic market collection. Powered by the 6640 caliber with 22j jewels beating at 36,000 bph, it delivers a 44 hours power reserve. [seikata-wm-e5d5ece2d656]

Also known as: Baby Tuna

Specifications

Movement

Hand-Winding

Case Material

Hardlex-Coated Steel

Case Width

36mm

Case Thickness

9.6mm

Lug Width

22mm

Crystal

Mineral

Bezel

Fixed

Water Resistance

90m

Dial Color

Burgundy

Jewels

22j

Frequency

36,000 bph

Power Reserve

44 hours

Year

1978

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