Seiko Cal. 6640 - 621

The Seiko 6640-621 represents an important milestone in Seiko's 1974 lineup. It features a Black dial protected by a Sapphire crystal and offers 30m of water resistance. [seikata-wm-06c5f66bc00a]

Also known as: Helmet

Specifications

Movement

Spring Drive

Case Material

Two-Tone

Case Width

46mm

Case Thickness

15.4mm

Lug Width

20mm

Crystal

Sapphire

Bezel

Rotating

Water Resistance

30m

Dial Color

Black

Jewels

33j

Frequency

21,600 bph

Power Reserve

46 hours

Year

1974

Related Models

• Seiko 4555-734
• Seiko 5676-598
• Seiko 6245-377
• Seiko 6231-918
• Seiko 7170-464
• Seiko 6265-739
• Seiko 5230-857
• Seiko 6226-986
• Seiko 0787-403
• Seiko 7083-701
• Seiko 4436-977
• Seiko 6276-358