Seiko Cal. 4431 - 640

The Seiko 4431-640 represents an important milestone in Seiko's 1965 lineup. The Inner Rotating bezel and 41mm case give it a distinctive presence on the wrist. [seikata-wm-0fe091d033b6]

Specifications

Movement

Spring Drive

Case Material

Gold-Plated

Case Width

41mm

Case Thickness

9.4mm

Lug Width

21mm

Crystal

Acrylic

Bezel

Inner Rotating

Water Resistance

40m

Dial Color

Green

Jewels

20j

Frequency

36,000 bph

Power Reserve

38 hours

Year

1965

Related Models

• Seiko 6360-634
• Seiko 3888-848
• Seiko 3823-680
• Seiko 0729-214
• Seiko 4486-940
• Seiko 6694-780
• Seiko 7066-385
• Seiko 5613-153
• Seiko 6372-578
• Seiko 6667-204
• Seiko 6626-522
• Seiko 6129-201