Every ship is designed around a particular class of hull - tiny, small, cargo, medium, large, and huge - and has a predetermined number of hit points and capacity. Each ship component fills a certain amount of space. Technological advances can lead to enhanced components that use less space (but typically cost more to construct). Players can upgrade existing ships to use these new components, although it is often cheaper to use them as cannon fodder and replace them with newer ships. There are three types of paired offense-defense mechanisms: