That's a pic of the one the Los Angeles County Sheriff's use.
It produces 15,000 watts of sound waves. The waves are so powerful you can hear a song being played crystal clear at over a mile away.
Some military LRADs bump it up to 100,000 watts. At close range the decibels of sound can cause instant deafness, brain trauma and nausia. Your head would in essence feel like its inside a concert size speaker box going full blast.
The systems were developed after the USS Cole attack and are now deployed on naval vessels worldwide including cruise ships.
Allegedly the NYPD tested one out during the protests at the Republican National Convention in NYC.