If you want to warn the next town over that you're on the way, then you can do so with the Kleinn Dual Truck Horn Kit. This kit includes a pair of chrome metal trumpets that measure 16.75", and 14.5" in length. Think of fire truck or ambulance horns but louder. Like loud enough to shake the dust off the Sierra Nevadas. The flat edge design on these horns allows for simple mounting behind your grille, in the engine bay, or even on a frame rail. This is a 120 PSI air system that will come provided with a 0.5 gallon air tank.
Here are further details:
Dual truck air horn
12-volt electronic solenoid
120 PSI air compressor
0.5-gallon air tank
Pressure switch (90 PSI on, 120 PSI off)
Drain valve, safety valve and outlet air fitting
Steel braided leader hose with check valve
"Snorkel" remote air intake
12 ft high-pressure nylon air tubing
Horn button
30/40 amp relay
30 amp fuse & fuse holder
Teflon thread tape
Mounting hardware
Installation instructions