The prototypical stun grenade is comparable to an oversized flash-cracker, producing a very loud bang and a bright flash while expelling low-density fragments that are less lethal than the harder materials in standard grenades. The bright light and loud sound of the stun grenade are designed to surprise and temporarily incapacitate persons in the targeted area to permit an immediate entrance by attack personnel under less dangerous circumstances. This article describes the various types of stun grenades, with some more likely than others to inflict injury, and tactical determinants are then listed. The importance of attack timing is emphasized, and suitable weapons for use in an attack involving stun grenades are indicated. An essential part of the planning for the use of stun grenades is noted to be preparation of all officers within the inner perimeter for the imminent attack, so they may don red goggles to preserve their vision. It is cautioned that stun grenades have no recognized standard for performance, and there is no firm legal or medical standard for what constitutes 'acceptable damage' to hostages. This raises issues of police liability in the use of stun grenades. Still, their use should be considered in certain extreme hostage situations.