Beam focusers in the reactor of the Executor-class Star Dreadnought Terror

"Shoot out the beam focusers. The reactor should go critical and blow, taking this ship and all these blasted fighters with it."
―Ru Murleen[src]

Beam focusers were a component of the main reactor on Executor-class Star Dreadnoughts. During an infiltration mission aboard the Executor-class Star Dreadnought Terror, Rebel pilots Rookie One and Ru Murleen destroyed the beam focusers in the ship's reactor, causing it to go critical and explode.