XM82

More popularly known as a Flashbang. It's a little known fact, but the British SAS were the first to develop the modern version of this weapon (though the Japanese Ninja reputedly had primitive version, the 'nageteppo' in their time). The Stun or Concussion Grenade is a canister-shaped device whose primary use is to stun or temporarily disable a terrorist without actually harming them; a very important point if the terrorist is holding a hostage or if it is desired to take the terrorist alive.

The XM82 Flashbang lives up to its name; upon exploding, it produces both a blinding flash and a deafening explosive sound. The air pressure from the blast can disrupt a person's eardrums, and likewise their balancing organs, while the blinding flash impairs vision. At close enough range and cramped quarters, the concussive blast of the grenade can knock out a person.

There is another kind of stun grenade called a "Stinger" grenade. It is a grenade based on the M67 Defensive design packed with solid rubber pellets that spray outward at high speed and can seriously injure, but not kill, an enemy. These kinds of grenades are used by certain maximum-security prisons in the US, but are not as effective as Flashbangs (since the high-speed rubber pellets can injure hostages as well as terrorists). The Stun Grenades in MGS/MGS2 are of the XM82 variety.

Real-life Counterterrorists find Flashbangs far more useful than normal grenades, especially when in delicate hostage-rescue situations. Despite their 'stun grenade' moniker, direct contact with a flashbang can still maim or kill a target.