This highly effective 12 gauge round produces a stun/diversion effect by using a bright blinding flash with an extremely powerful concussion blast from a 12 gauge shotgun muzzle. This device is not restricted by the BATF and is used by some of the most elite special forces and SWAT units around the world. It produces 182dB bang, 1.5 to 2 million candle flash and over pressure on 1.5 to 2 atmospheric pressure units. It is truly an awesome experience indoors and out. Will not work in 12 Gauge Flare pistol. 1 3/4" round