Seiko Cal. 6638 - 740

Seiko 6638-740

The 6638-740 is a sought-after Spring Drive piece from Seiko's golden era. Powered by the 6638 caliber with 21j jewels beating at 21,600 bph, it delivers a 45 hours power reserve. [seikata-wm-a077d1570b0b]

Also known as: Rally

Specifications

Movement
Spring Drive
Case Material
Hardlex-Coated Steel
Case Width
45mm
Case Thickness
13.3mm
Lug Width
21mm
Crystal
Mineral
Bezel
Bidirectional
Water Resistance
200m
Dial Color
White
Jewels
21j
Frequency
21,600 bph
Power Reserve
45 hours
Year
1983

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