Seiko Cal. 6640 - 721

The 6640-721 is a sought-after Hand-Winding piece from Seiko's golden era. Powered by the 6640 caliber with 26j jewels beating at 28,800 bph, it delivers a 72 hours power reserve. [seikata-wm-a624a0e00c41]

Also known as: Bullhead

Specifications

Movement

Hand-Winding

Case Material

Two-Tone

Case Width

36mm

Case Thickness

14.6mm

Lug Width

20mm

Crystal

Hardlex

Bezel

Bidirectional

Water Resistance

170m

Dial Color

White

Jewels

26j

Frequency

28,800 bph

Power Reserve

72 hours

Year

1979

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