A telepresence unit was a device which utilized telepresence to allow a person to safely control a vessel from a remote location. Telepathy was required to use a telepresence unit, which could transmit brain wave signals through many light years in space.
In the final draft script of "Babel One", the Romulan telepresence unit was referred to as a type of synaptic interface. The script also made it clear that the unit, describing it as "helmet-like", was to cover the wearer's antennae and ears in order to hide the wearer's species as Aenar, rather than Romulan.
In the final draft script of "The Aenar", the telepresence unit constructed aboard Enterprise was described thus; "It's a jury-rigged, hi-tech apparatus that will ultimately consist of a swiveling chair flanked by controls, monitors, electronic modules, connecting cables, etc." Also, aboard Enterprise, that unit was scripted to be assembled in launch bay 2, whereas it is actually shown being assembled in sickbay.