The beginning of the end in many hostage dramas occurs when a SWAT team tosses a stun grenade into a room to disorient the bad guys with a loud, blinding explosion. While generally harmless, stun grenades can sometimes injure hostages. So researcher Mark Grubelich and colleagues at Sandia National Laboratories in Albuquerque, New Mexico, have come up with a kinder, gentler version.

Existing grenades contain a concentrated mixture of aluminium and potassium perchlorate that combines violently with a salt containing oxygen when ignited by a fuse. The result is a wave of high pressure that can be harmful to eyes or ears. The new Sandia device contains only 20 grams of fine aluminium powder and no oxidizer. And instead of being ignited, the particles are expelled in a 5-foot-wide arc through 16 quarter-inch holes in the bottom of the plastic container. The particles ignite when they come into contact with oxygen in the air, spreading out rather like a cloud of pixie dust. This approach lowers the pressure in the immediate area of the explosion, making injuries less likely. And the coup de grace: Sandia stun grenades are also reuseable–just plop the casing in a dishwasher and you’re ready to go again–which makes training less expensive and, therefore, easier.