Guaranteed to scare the hell out of idiot cage drivers who do stupid chit ! (maybe)
What is a Banshee Horn you bricKhead's ask ?
http://tinyurl.com/BansheeHORNTechnically Speaking:
The electronics in this product control the loud air horn and the high beam lights. If you press the horn switch briefly, only the regular horn is activated. Pressing the switch for ¼ or ½ second (depending on the setting you choose) causes the logic in the control unit to now engage the raucous air horn and high beam lights. When doing this, it pulses both the horn and lights for even greater impact - as shown in the video.
When designing the electronics we paid particular attention to safety. We do not in any way alter the regular horn system in the motorcycle or car to keep within DOT (Dept of Transportation) regulations.
Also, we don’t put any electrical loads on the existing vehicle wiring because we take our power directly from the battery.

Smart Design using Quality Parts:
This product is made up of two components, a 139 decibel compact air horn and a control unit that is really what this product is all about.
The control unit is about the size of a matchbox and the internal parts will be sealed in resin. This creates a water, heat and vibration proof environment which in turn provides superior reliability.
It has been tested in extreme temperatures (from 10 - 160 degrees Fahrenheit), and works faultlessly.