The Son'a metaphasic collector, also refered to as the Injector, was a massive spacecraft designed by the Son'a for the specific purpose of harvesting metaphasic radiation from the rings of Ba'ku. The collector was designed to launch an injector assembly that would produce a cascading thermolitic reaction within the rings, allowing the collector to harvest the radiation that emanated from them. A major side effect of this process, however, was that the planet would be rendered uninhabitable for generations.
With the assistance of the Federation, the Son'a were able to finally deploy the collector in 2375. Fortunately, the collector was disabled moments before it could launch the injector when Jean-Luc Picard, Worf, and Subahdar Gallatin commandeered Ru'afo's flagship and deactivated the collector. However, Ahdar Ru'afo managed to transport aboard the collector shortly thereafter and raise its shields. Picard, nevertheless, managed to beam aboard by transporting between the shield generators and reactivate the collector's self-destruct sequence. Picard was beamed away seconds later by the USS Enterprise-E, but Ru'afo was killed when the collector exploded. (Star Trek: Insurrection)
Background information Edit
Only intended to be a CGI model, the Son'a collector was designed by John Eaves; the computer-generated exterior model having been built by Santa Barbara Studios. It was intended to be 5000 feet (1524 meters) long, but Eaves noted that the scaling for the vessel was problematic throughout the movie.  The sails of the Son'a collector were very similar to those used in Bajoran lightships. The collectors' sails, however, served a purpose completely unlike those of the lightship.
In scene 246 of the final script version, the collector is also referred to as "THE SON'A SCIENCE VESSEL", a designation adhered to by its designer John Eaves. (The Secrets of Star Trek: Insurrection, pp. 92-93) The Star Trek Customizable Card Game gives its name as Injector Assembly One.