It's the Long Range Accoustical Device or LRAD. Used by jackbooted thugs to control crowds and pirates etc... Here is it being used in at the G20 summit in 2009
and the thing that should piss us all off is that now they are going to be shipped to every major city.
LRAD Sonic Weapons To Be Deployed “Throughout” America For Crises | Global Unrest:
They are worried about something, otherwise they wouldn't feel the need to arm themselves like this against citizens....
HT to Wirecutter
'via Blog this'