Photon torpedoes are self-propelled, warp-capable projectiles containing small amounts of matter and antimatter. The matter and antimatter are bound together in a magnetic bottle that is broken on impact, unleashing the destructive energy of the mutual annihilation. Photorps, as they are sometimes called, are the weapon of choice when starships are traveling at warp speed as they are not limited by the speed of light. Photon torpedoes can have their warheads removed and replaced with sensor packages or left hollow to transport small objects. Galaxy-class starships can launch up to ten independently-targeted photon torpedoes from a single tube.