A flashbang is a type of explosive device which is designed to create a very disorienting flash and bang. It is classified among the grenade family of explosives, since it is designed to be activated and then thrown or launched before it explodes. The advantage to a flashbang is that it does not generate shrapnel, making it ideal for situations in which innocent bystanders could be hurt. Law enforcement teams which specialize in defusing tense or confusing situations often carry flashbangs because these devices can be used to control groups of people without injuring them.
When a flashbang is detonated, it produces an extremely bright flash of light which temporarily overstimulates the retina. As a result, people cannot see for around five to 10 seconds; since most people prefer to remain stationary when they are visually disoriented, the flash can bring the people involved in a situation to a temporary halt which can allow members of law enforcement to quickly move in and take control. The deafening bang also contributes to feelings of disorientation; depending on one's proximity to the device, it can cause a lingering ringing feeling in the ears.
Under safe conditions, a flashbang is totally harmless, although disorienting. However, they do contain explosives, and as a result, they can trigger secondary explosions. This is a risk which should be considered when working in volatile environments; gas leaks, for example, can fireball when a flashbang is detonated, and methamphetamine labs can explode. Law enforcement personnel are expected to consider prevailing conditions before detonating a flashbang grenade.
These devices are used in crowd and riot control and to defuse hostage situations. It is standard policy in many law enforcement communities to toss a flashbang grenade into the door when entering the site of a standoff, to ensure a safe surrender of those involved by incapacitating them as law enforcement moves in. In riot control, a flashbang can be a very effective tool, because it gives law enforcement personnel the upper hand. Flashbangs are also useful in war zones where civilians are mixed with combatants, because soldiers can neutralize everyone within an area while they figure out who is who.
Several companies manufacture various styles of flashbang grenades which are sold to military and law enforcement organizations. It is also theoretically possible to make your own, although it is not recommended unless you have a good reason to do so and explosives experience. Consumers should also be aware that the possession of all grenades including flashbangs is restricted in many parts of the world.