[3][4] The M84 features a pyrotechnic metal-oxidant mix of magnesium & ammonium inside a thin aluminum case, contained within a perforated cast steel body.

Unlike the high explosives (HE) used in traditional ordnance, the pyrotechnic charge produces a subsonic deflagration, not a supersonic detonation, minimizing the blast effects.

On initiation, the auditory and visual elements of the deflagration are permitted to escape via the perforations in the cast outer body.

It is intended to be thrown into enclosed spaces to distract and temporarily incapacitate enemy personnel for easier capture, or when risk of collateral damage during urban warfare or hostage rescue operations contravenes the employment of traditionally lethal and destructive fragmenting high explosive ordnance.

US Army doctrine calls for the M84 to be deployed "during building and room clearing operations, when the presence of noncombatants is likely or expected and the assault element is attempting to achieve surprise.