Seiko Cal. 5631 - 687

The Seiko 5631-687 represents an important milestone in Seiko's 1971 lineup. The Bidirectional bezel and 39mm case give it a distinctive presence on the wrist. [seikata-wm-1bd39e1760b8]

Also known as: Sportsmatic

Specifications

Movement

Solar

Case Material

Hardlex-Coated Steel

Case Width

39mm

Case Thickness

10.6mm

Lug Width

18mm

Crystal

Sapphire

Bezel

Bidirectional

Water Resistance

30m

Dial Color

Champagne

Jewels

28j

Frequency

36,000 bph

Power Reserve

52 hours

Year

1971

Related Models

• Seiko 7182-662
• Seiko 7097-501
• Seiko 3826-310
• Seiko 6653-564
• Seiko 6627-460
• Seiko 6633-605
• Seiko 6396-462
• Seiko 4537-526
• Seiko 7194-193
• Seiko 6314-607
• Seiko 4448-556
• Seiko 7199-130