Sonic grenade

Little is known about these grenades, other than that several of these were used by Colonel James Ackerson in testing the MJOLNIR Mark V armor on Reach, hidden amongst the Pillars of Loki and used in conjunction with Napalm Grenades.

Theories

 * This grenade is similar to a Fragmentation Grenade in structure and detonation, except that it uses a miniature sonic boom rather than explosives. The grenade is not as effective as a Frag, but it is still effective and operative.
 * The grenade is a non-lethal weapon used by Drill Instructors to teach Marines to keep their eyes peeled, hitting them with a loud sound that hurts their ears rather than actually causing them bodily harm. It would be one of the nicer booby traps used by DIs.

Trivia

 * They're probably similar to the Star Wars Sonic Detonators as they use high frequency sounds to incapacitate targets.
 * These grenades cannot be used by the player for they are not seen or used in the Halo Trilogy.
 * Their use as a non-lethal measure means they could be compared to presently used flashbang grenades.