The 5600 family of movements was produced by Suwa Seikosha from 1968 through 1976. It was designed for mechanized production and featured many updated details, including quickset day and date.
Unlike many other contemporary Seiko movements, the 56 series uses a conventional reverser gear for the automatic winding system rather than Seiko’s Magic Lever system.
| Lord Matic 21,600 | King Seiko 28,800 | Grand Seiko 28,800 | |
| No Date | 5601A | 5621A 5621B | 5641A |
| Date Only | 5605A | 5625A 5625B | 5645A |
| Day-Date | 5606A | 5626A 5626B | 5646A |
| Date and GMT | 5619A |