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A motion scanner is a small, handheld, long-range motion detector used by the Covenant. Motion sensors were given to small Covenant forces, such as Grunts, who were then sent to the edge of an encampment or strong point. They could then detect incoming units and vehicles and sound an alarm.

In 2552, during the Fall of Reach, Zawaz was assigned to be a lookout with a motion scanner for the landing zone of a Covenant cruiser. He detected a team of Spartans, and thought that they were Elites on some secret mission so did not set off the alarm, and the three SPARTAN-IIs destroyed the zone.