Viair 20055 Onboard Air Hookup Kit VIAIR's onboard air hook up kit is everything you need to create an onboard air system except the VIAIR compressor Comes with a dash panel on/off switch and pressure gauge. Includes fittings, wiring, air hose, pressure switch with a built in relay. Pressure Range is 90 to 120PSI. Design your own onboard air system for your vehicle. Refer to manufacturer's website for wiring diagram.