From the Star Trek: The Next Generation episode "Starship Mine".

I purchased this online.

This was sold to me by a dude online who claimed that it was screen used. I have no way to confirm or deny if it was screen used, but I usually doubt those types of claims. Either way, it's a really nice piece and was worth what I paid either way. I beleive this is from the episode of TNG where the Enterprise gets caught in this asteroid field where each of the asteroids has some mine in it that sucks the energy out of a ship. I think this com belonged to one of the aliens that was on the derelict ship that the Enterprise finds floating around inside. John Broughton tells me: The Alien Communicator Com badge was from the TNG episode, Starship Mine. Terrorists used these comm badges while sucking trilithium from the Enterprise prior to a "Barrian Sweep". Mike Goobic Tells me: The "Alien Communicator" appeared in several ST:TNG and ST:V episodes: "Starship Mine" is was a combadge; and in a certain Voyager episode it was a combadge and lastly, Elvis Algate tells me: the "alien communicator" in your TNG prop collection is in fact seen in the episode "Starship Mine," where a group of profit-opportunists attempt to steal some trilithium residue from the warp core of the Ent-D, for a terrorist group. They decide to do so while the ship is being cleansed in orbit of the planet Arkania (using a Barion sweep; a method of cleaning a ship of all possibly harmful biological residue, and is known is to be lethal to anything organic that comes in contact with it). Capt. Picard happens to be stuck on the ship with this group, and thwarts their attempts. The communicator was worn on an armband on each member of the group. And, well, there you have it. Thanks for the tips, guys!