The Omicron class was a type of structure used by the Romulan Star Empire.
This type of shield generator was a typical example of Romulan technology as it was delicate yet a technically advanced machine that ran at the peak of performance for a long period of time. The brutal regimen that it suffered from meant that the system was a pared-down thoroughbred device as the failure of the shield's meant that the colony it protected (along with its colonists) would be lost. The deflector emitter was found at the lower generation ring whilst the smaller upper ring acted as a stabilizer which balanced the system's output to the shield. The elegance of the design meant that the power needs were less than the Klingon Empire's and the Federation's counterparts. Despite this being the case, it was considered the most power hungry structure present at a colony. (TOS video game: New Worlds)