The movement in this Omega Seamaster Replica is the Omega caliber 2628 with 44 hours power reserve, it is a modified ETA-2892-A2 that includes the famed Omega co-axial escapement. Once you unscrew the well protected crown, the hours hand can be quickly changed accurately while the seconds, minutes, and GMT are still functioning. Pulling the crown once more stops the seconds hand and allows the minutes hand to move along with the GMT hand. There is a hacking seconds feature that allows the time to be set more precisely.
Unlike most other Omega Replica Watch, the Seamaster 300 M GMT Professional contains a display caseback showing the rhodium-plated decorated movement with the Omega logo and name inscribed on the automatic rotor.