Entry Plug

An Entry Plug is a long, capsule-shaped object contains the cockpit (and by the extension, the pilot) for an Evangelion Unit. Entry Plugs are inserted into the spinal area of an Evangelion via a loading mechanism, after which it spins inwards and locks itself into the Eva's torso. Standard Entry Plugs are white. However, those used in the remote-control Dummy Plug system are red. Entry Plugs appear to be immensely strong in construction. Examples include Eva-00's entry plug surviving the Eva's destruction in one piece while most of Tokyo-3 was turned into a crater, and Eva-01 took several seconds to crush the infected Eva-03's entry plug.

A Stop Signal Plug is loaded into an Evangelion after the Entry Plug has been removed, when the Eva is no longer being operated..

Signal Termination Plug

A Signal Termination Plug seems to be an added means of making sure that an Eva will not start up on its own, while it is being stored and the Eva is not being used. The end of the Signal Termination Plug that sticks out of the back of an Evangelion is shaped like a crucifix.

The Signal Temrination Plug is most prominently seen in Episode 02 and Episode 05, when Evangelion Unit-00 is frozen in bakelite after it lost control during an experiment. However, a Signal Termination Plug is seen again (very briefly and in a dark shot) in Episode 11, when it has to be manually removed from an Evangelion so that an Entry Plug can be loaded in.