A Jump Pack is a back-mounted device containing jets powerful enough to lift even a Space Marine wearing power armor. It allows a warrior to travel quickly across the battlefield, leaping over obstacles and launching himself into close combat.
Players can use a Jump Pack in specific stages of the single-player campaign. As seen in the introduction sequence of the campaign, a Jump Pack can be used to allow a Space Marine to perform a deep strike deployment onto a planetary surface from high altitude, though this is not directly performed in gameplay.
In multiplayer (both in adversarial Versus and Exterminatus modes), Jump Packs are always available, but limited to the Loyalist Assault and Chaos Raptor classes.