Son'a drones were small automated flying devices used by the Son'a, capable of shooting isolinear tags. These probes were capable to pursuing moving humanoids, targeting them and firing dart-like tags onto them.
In 2375, two Son'a shuttles launched several dozen drones on Ba'ku when their transporters were unable to lock on to the escaping Ba'ku and Starfleet personnel. At least fourteen drones were destroyed in the pursuit. (Star Trek: Insurrection)