TooJay, more formally known as 2JTJ, was a navigation droid given to Master Tahl by the Jedi Order following her loss of sight on Melida/Daan.
Following her injury, 2JTJ aided Tahl in adjusting to her blindness by offering support as she acclimated to her changed circumstances. Unbeknownst to them, the disgraced Jedi Xanatos had placed a hidden audio-visual surveillance system within the droid to monitor the activities of Qui-Gon Jinn and Tahl. Upon uncovering this deception, they set a snare for Xanatos. Subsequently, 2JTJ remained in Tahl's service.