Keepers, or station keepers, are only ships in the technical sense. The Galactic Council views them as mobile system defense installations, basically enormous space stations that can move between systems. Of the three ships currently under construction, only one is consistently funded, though the two ships currently deployed are a very mobile and visible representation of the Council’s power. Two corporations are also constructing their own keepers, with several more possibly planning them in the future.
Keepers are enormous, massing at more than a trillion metric tons, and hitting diameters close to that of Earth’s original moon. With a theoretical maximum capacity measured in tens of millions, keepers are more like the deep space stations constructed before and immediately after the Alien War than any ship. While they don’t mass quite as high as those stations, the keepers are mobile, generating enough power to create enormous wormholes through a number of large singularities. The wormholes they create are so large, in fact, that a keeper emerging from a wormhole within 1 au of an inhabited planet can cause undesirable radiation exposure to the planets themselves. As such, keepers will usually approach a planet under sub-light power or use smaller fleet craft inside of a star system.
Each keeper is designed individually, instead of based around mark numbers like the battlehulks had been. Keepers function as enormous mobile cities as well as virtually impregnable weapons platforms. Civilian contractors are kept aboard under most circumstances, and many soldiers chose to keep their families aboard with them. Under normal circumstances, this would be considered dangerous. But keepers have proven themselves to withstand attacks from fleet carrier groups and Mark VII battlehulks without any loss of life, leading to the conclusion that it’s safer aboard a station keeper than it is on the surface of a planet.