In order to make the most efficient use of their lone deepspace shipyard, the Seven Suns consortium produced only three classes of vessels: cruisers, heavy merchant vessels, and raiders. Of these three vessel types, the most numerous by far were the Septisolaran Raiders.
The Septisolaran Raider is essentially a light freighter hull equipped with anti-ship weapons and over-sized maneuvering thrusters all sandwiched between two thick shells of starship armor. The Seven Houses of the Consortium use these hardy vessels for a variety of purposes: warships, raiders, smuggling vessels, and light merchants.