Seiko Cal. 6640 - 900

Released in 1969, the Cal. 6640 with design code 900 was part of Seiko's domestic market collection. It features a Navy dial protected by a Sapphire crystal and offers 80m of water resistance. [seikata-wm-06ad61efe316]

Specifications

Movement

Automatic

Case Material

Hardlex-Coated Steel

Case Width

36mm

Case Thickness

8.9mm

Lug Width

21mm

Crystal

Sapphire

Bezel

Coin-Edge

Water Resistance

80m

Dial Color

Navy

Jewels

30j

Frequency

21,600 bph

Power Reserve

49 hours

Year

1969

Related Models

• Seiko 6178-818
• Seiko 5631-792
• Seiko 6322-478
• Seiko 4473-713
• Seiko 7077-886
• Seiko 4558-639
• Seiko 7068-217
• Seiko 5654-901
• Seiko 5275-960
• Seiko 4579-556
• Seiko 6250-274
• Seiko 4587-565