Seiko Cal. 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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