A
concussion grenade, also known by the terms
stun grenade,
flashbang and
noisemaker, is a hand-thrown
explosive device. Like its more
lethal cousins, it is designed to be armed by removal of a pin and then the subsequent release of an
arming 'spoon,' after which a
chemical fuse begins to run. The primary characteristic of a concussion grenade is that it is designed to be
non-lethal. Rather than harming its target through
shrapnel (the most lethal part of a typical
grenade explosion, which - contrary to television - typically involves almost no flame) it is intended to produce a very sharp, strong
report. The pressure wave from this
detonation is meant to be strong enough to temporarily
stun or incapacitate humans. The casing of such a grenade is made from paper or a soft plastic which will dissolve or powder in the explosion and present minimal damage risks. Some models also contain
magnesium or other
pyrotechnics designed to produce an extremely bright flash of light; experiments and experience have shown that humans can be rendered immobile and/or given temporary
seizures by bright and sudden enough flashes which overload the
optic nerves and that part of the brain responsible for vision. When coupled with the concussion, these are very effective. They can also be used to destroy the vision of enemies using
night vision equipment.
These are popular with special police units, such as Hostage Rescue teams and S.W.A.T. units. They are also used by the military, particularly in urban combat, where the enclosed spaces of buildings, tunnels and vehicles amplify their effect through resonance.