Seiko Cal. 3881 - 631

The 3881-631 is a sought-after Automatic piece from Seiko's golden era. Powered by the 3881 caliber with 36j jewels beating at 36,000 bph, it delivers a 39 hours power reserve. [seikata-wm-8992d52eac6e]

Also known as: Tuna, Helmet

Specifications

Movement

Automatic

Case Material

PVD Black

Case Width

37mm

Case Thickness

10.9mm

Lug Width

20mm

Crystal

Sapphire

Bezel

Rotating

Water Resistance

100m

Dial Color

Green

Jewels

36j

Frequency

36,000 bph

Power Reserve

39 hours

Year

1965

Related Models

• Seiko 5689-761
• Seiko 6145-401
• Seiko 7078-993
• Seiko 5257-546
• Seiko 7021-207
• Seiko 5682-744
• Seiko 6693-515
• Seiko 5254-752
• Seiko 5644-594
• Seiko 4476-424
• Seiko 7092-450
• Seiko 6392-291