Kleinn Air Horns 7275 Onboard Air 150 All-In-One Air System comes plumbed with all required fittings and wired with a pressure switch that will turn the unit on and off at preset pressure. The Onboard Air 150 features a 50-percent duty cycle air compressor sitting atop a 2-gallon air tank, producing 150-PSI. Depending on your application, Onboard Air Systems are perfect to supply compressed air for virtually any mobile need. They’re also great when paired with any Kleinn air horn. It is easy-to-install and is perfect for most automotive needs. It works very well as a stand-alone air source, or when paired with any of our best-selling air horns. Too Loud? Too Bad.