Presenting the KO (Knock-off) version of Optimus Prime's UFO Annular Trailer.
The UFO Annular Trailer is based upon the trailer of Optimus Prime as it appeared in the Transformers Dark of the Moon movie when Prime first encountered Shockwave and his driller. Prime's trailer transformed in the movie and became a circular structure bristling with weapons from which Optimus Prime drew a sword and a shield (Since he loves beheading Decepticons a lot).
Later in the movie Optimus Prime would state the need to recover his trailer because he needed the flight technology within it.
