A small prototype device worn on the body that can beam one person to safety once, used by Data to save Captain Picard from the Scimitar in Star Trek Nemesis.
The emergency transport unit is a miniature transporter about the size of a badge. It carries enough power for one transport of one person to preset coordinates. In 2379 it is still a prototype, which Data shows to Picard aboard the Enterprise-E.
It appears only in the film Star Trek Nemesis, where its single-use limit is made clear well before the final battle with Shinzon's warship Scimitar.
In the climax, with the Enterprise's transporters down, Data leaps across open space to the Scimitar, finds Picard standing over the dead Shinzon and presses the unit onto his captain's uniform. Picard is beamed home, and Data stays behind to destroy the thalaron generator, sacrificing himself.