Seiko Cal. 6638 - 731

Seiko 6638-731

This Solar model from 1977 features a 34mm Titanium case. Powered by the 6638 caliber with 36j jewels beating at 21,600 bph, it delivers a 63 hours power reserve. [seikata-wm-c57b82a9bcbf]

Also known as: Sumo, Tuna

Specifications

Movement
Solar
Case Material
Titanium
Case Width
34mm
Case Thickness
9.2mm
Lug Width
21mm
Crystal
Hardlex
Bezel
Bidirectional
Water Resistance
180m
Dial Color
Burgundy
Jewels
36j
Frequency
21,600 bph
Power Reserve
63 hours
Year
1977

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