Seiko 4420A (44KS)
ProbableThe 44KS caliber, and a Daini Seikosha product. Its two-digit family code is why King Seiko references of this era read '44-9990' rather than as a four-digit case number — the standard Seiko reference parsing does not apply to them.
Specifications
- Movement manufacturer
- Seiko
- Production
- 1964–1968
- Frequency
- 18,000 vph (2.50 Hz)
- Jewels
- 25
- Winding
- manual
Architecture
Manual-wind high-accuracy caliber developed by Daini Seikosha for King Seiko.
References using this caliber
- Seiko 44-9990Factory
King Seiko · 1964–1968
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 referenceProbable
Secondary sourceCollector research
Plus9Time — Seiko case back, case numbering and model research
Plus9Time
- Accessed
- 2026-08-18
Cited for
This referenceProbable
Last verified: Not yet reviewed