Let’em know you’re there with Pacbrake’s air horns. Our easy to install air horn kits come with a 12V solenoid , airline, mounting hardware, brass fittings, and chrome plated air horns. Max sound output is 120 db / 235 hz with a max operating pressure of 12 - 110 PSI. For operation, the vehicle must have onboard air. If your vehicle does not have onboard air already, you may be interested in checking out Pacbrake’s Onboard Air Accessories.