The T7 series represented a line of astromech droids that saw usage back in the era of the Old Republic, with notable deployment during the Great Galactic War.
A specific droid of this type (one) found itself in the hands of Nico Okarr, a smuggler, during the tumultuous times of the Great Galactic War, eventually transferring into the ownership of the Jedi Knight celebrated as the Hero of Tython.
In approximately 3643 BBY, certain individuals believed that the combat enhancements produced for the T7 line on Nar Shaddaa were among the best one could acquire.