Seiko Cal. 6631 - 901

The 6631-901 is a sought-after Solar piece from Seiko's golden era. Powered by the 6631 caliber with 22j jewels beating at 28,800 bph, it delivers a 54 hours power reserve. [seikata-wm-a87732d2b689]

Also known as: Bullhead, Emperor

Specifications

Movement

Solar

Case Material

PVD Black

Case Width

42mm

Case Thickness

13.3mm

Lug Width

22mm

Crystal

Mineral

Bezel

Bidirectional

Water Resistance

170m

Dial Color

White

Jewels

22j

Frequency

28,800 bph

Power Reserve

54 hours

Year

1978

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