Seiko 4006A
High confidenceThe Bell-Matic caliber. Because the alarm sounds against the caseback, the movement and the case form one acoustic system — the alarm cannot be assessed with the caseback off, and a wrong caseback will mute a perfectly good alarm.
Specifications
- Movement manufacturer
- Seiko
- Production
- 1967–1978
- Frequency
- 21,600 vph (3 Hz)
- Jewels
- 27
- Winding
- automatic
- Complications
- Day-date · Mechanical alarm
Architecture
Automatic caliber with a mechanical alarm, the hammer striking a pin in the caseback.
References using this caliber
- Seiko 4006-7000Factory
Vintage · 1967–1978
Provenance of this record
Sources & Evidence
Primary sourceTechnical documentation
Seiko caliber technical guides and parts catalogues
Seiko Watch Corporation / Seiko Instruments
- Accessed
- 2026-08-18
Cited for
This referenceHigh confidence
Last verified: Not yet reviewed