Concussion grenade
From Halopedia, the Halo wiki
Concussion grenades are antipersonnel devices that are designed to damage its target with explosive power alone. Compared to fragmentation grenades, the explosive filler is usually of a greater weight and volume. The case is far thinner and is designed to fragment as little as possible. The shock wave overpressure produced by this grenade when used in enclosed areas is greater than that produced by the fragmentation grenade. Therefore, it is especially effective in enclosed areas.
