I seen this on a few cars. Recently, I seen it on this Acura Integra. It's located behind your rear view mirror. So, people on the outside can it when they look at your windshield. It's more like a len strip, and it flashes blue moving back/forth; kind of like the Knight Rider thing. Anyone know what I'm talking about? I know those people only turn them on when their cars are parked, and not have them on while driving around. I think that would be illegal.
Wish I know where I can get these.

 

my friend got one at some audio/stereo store in houston........you can prolly get em at aftermarket car stores.

 

crutchfield sells red ones.

 

they sell them at car audio shops, I've seen them, and yes, they're called scanners.

The blue one looks pretty nice i think.

Chris