The Chiroptera-class Prowler was a Small star ship type used by the Office of Naval Intelligence. Chiroptera-class Prowlers were used by the UNSC in the early 2500's, but in 2512. all vessels of this class were decomissioned and sold for scrap. They were decomissioned because they broke down constantly and had far to many sensitive components without a central controlling AI. They did, however, have the smallest operational slipspace engines ever produced. Chiroptera-class vessels were roughly fifty meters long with oddly angled black stealth surfaces. They also carried advanced counterintrusion software.
In 2552, Governor Jacob Jiles of the Eridanus Rebels came into posession of one of these, the Beatrice, and he used it as his personal ship, as well as "flagship" of his improvised fleet. Dr. Catherine Halsey stole this ship and used its slipspace drive to depart to places unknown.