Tetryon-based signaling device
A tetryon-based signaling device was made from components from a downed  Class 2 shuttle.

In 2378, Seven of Nine found pieces of a shuttlecraft she and Commander Chakotay were in before it was destroyed by an energy barrier on the planet Ledos. The barrier trapped both Seven and Chakotay inside it after they beamed off the shuttle. However, Seven was later able to open the barrier temporarily by connecting the tetyron-based signaling device to the destroyed shuttle's deflector. She had reservations of constructing the device in front of the pre-warp Ventu, as that would have violated the Prime Directive. ()
Communications technology