All units in "Homeworld 2" are starships of various classes, from small to large: Fighter, Corvette, Frigate and Capital Ship. Although the larger ships are more powerful and durable, they are also much slower and less maneuverable. Ships within each class specialize in certain areas and are vulnerable to certain other ships, although there may be ships in the same class that do not share the same vulnerability. Ion Cannon Frigates, for instance, are very vulnerable to fighters due to the unwieldy (albeit powerful) nature of their single weapon. Flak Frigates, however, are specifically intended for use against fighters, but lack the firepower to defend themselves against other frigates. Effective use of the relative strengths of each ship is essential for success.