Seiko Calibre 44 movement family

Designed by Daini Seikosha. Based on the Calibre 5440 found in the First King Seiko (which did not have the stop-seconds function).

44A

4402A

King Seiko Self Dater prototype dials

4402A 28,800 vph prototype

4419A instantaneous date change prototype - 1 or more known examples?

4420A - KSCM

4420B - Grand Seiko 44GS

4420B 57,600 vph prototype in KSCM 4420-9990 case - 2 known examples?

4420B 72,000 vph prototype in 4420-9000 44GS case - 3 known examples.