Seiko Cal. 6631 - 540

The 6631-540 is a sought-after Automatic piece from Seiko's golden era. Powered by the 6631 caliber with 25j jewels beating at 21,600 bph, it delivers a 65 hours power reserve. [seikata-wm-dd759d92bc39]

Also known as: Sumo, Navigator

Specifications

Movement

Automatic

Case Material

Titanium

Case Width

43mm

Case Thickness

12.7mm

Lug Width

19mm

Crystal

Acrylic

Bezel

Fixed

Water Resistance

150m

Dial Color

Green

Jewels

25j

Frequency

21,600 bph

Power Reserve

65 hours

Year

1978

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