The Omega 1120 is a mechanical movement with automatic winding, ball-bearing rotor, hacking seconds, power reserve 44 hours. It is based on the popular ETA 2892-A2 calibre and was the predecessor of the Omega 2500 with co-axial escapement.
Used for example in the series Seamaster.
Calibre 1128 adds a 24 hour hand.
Calibre 2400 is a skeletonized version of Cal. 1120 with no date function.
Calibre 2401 is a skeletonized version of Cal. 1120 with no date function in yellow gold.