The Grand Seiko caliber 4420 is a manual winding mechanical movement, introduced in 1967.
| Caliber | 4420 |
| Type | Mechanical Manual |
| Family | 44GS |
| Year | 1967 |
| Jewels | 27 |
| Bph | 18,000 |
| Complications | – |
| Technical information | Japanese |
Grand Seiko watches with caliber 4420
Ref. 4420-9000 (Diashock)
Movement: 4420
Type: manual
Jewels: 27
Bph: 18.000
Case: stainless steel
In the first version there is the Diashock writing under the Grand Seiko brand at 6 o’clock, which will soon be replaced by the Daini logo visible in the next version, with the same case-movement reference.
Ref. 4420-9000 (Daini logo)
Movement: 4420
Type: manual
Jewels: 27
Bph: 18.000
Case: stainless steel
Version of 4420-9000 with the Daini logo on the dial.
Ref. 4420-9990
Movement: 4420
Type: manual
Jewels: 27
Bph: 18.000
Case: gold cap
It shares the same case-movement reference as the King Seiko from which the 44GS series originated. The King Seiko 4420-9990 was available in stainless steel and gold cap, while the Grand Seiko 4420-9990 appears to have only been produced in the gold cap version.