Great when you don't have a lot of room
I have a Scion Xb Gen 2. Wanted a loud horn, but I didn't want to kill my trunk space. I mounted the compressor next to the spare tire and the trumpet under spare pointing to the right. So its great when I am passing some FLasshole who is texting and waking up folks about to step off the sidewalk. Mine is connected to the battery with a switch on the console and a relay under the dash. Great system and lots of fun. My toaster sounds like a tugboat!