Seiko Cal. 3840 - 820

Released in 1970, the Cal. 3840 with design code 820 was part of Seiko's domestic market collection. With its 19mm lug width and 8.9mm profile, it sits comfortably on most wrists. [seikata-wm-4ef543dbe26d]

Also known as: Tuna

Specifications

Movement

Automatic

Case Material

Hardlex-Coated Steel

Case Width

43mm

Case Thickness

8.9mm

Lug Width

19mm

Crystal

Acrylic

Bezel

Coin-Edge

Water Resistance

190m

Dial Color

White

Jewels

21j

Frequency

21,600 bph

Power Reserve

48 hours

Year

1970

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