Seiko Cal. 5631 - 538

Seiko 5631-538

The 5631-538 is a sought-after Spring Drive piece from Seiko's golden era. Powered by the 5631 caliber with 32j jewels beating at 28,800 bph, it delivers a 39 hours power reserve. [seikata-wm-c5c515cf0c80]

Also known as: Baby Tuna

Specifications

Movement
Spring Drive
Case Material
Two-Tone
Case Width
41mm
Case Thickness
9.4mm
Lug Width
22mm
Crystal
Sapphire
Bezel
Rotating
Water Resistance
160m
Dial Color
Black
Jewels
32j
Frequency
28,800 bph
Power Reserve
39 hours
Year
1965

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