One kind of bulk cruiser was produced by Keizar-Volvec and used by the Sith Empire as a command ship during the Great Galactic War. The more famous designs were produced during the Clone Wars, meant to be second-line Republic ships. Not deployed until after the conflict was over, they became among some of the most common designs seen in space, although most were modified, due to their stock design being prone to breakdowns, slow speed and expensive refueling. The term came to be used to describe a number of ships that fit the general characteristics.