Vixen Horns Loud 139dB 4/Quad Chrome Trumpet Train Air Horn with 1 Gallon Tank and 150 PSI Compressor Full/Complete Onboard System/Kit VXO8210/4114 Quad Trumpet Train Air Horn Tank Capacity: 1 Gallon (3 liter) 12 volt 150 PSI Compressor Thermal Overload Protection Mounting Hardware Included