Vixen Horns Loud 149dB 4/Quad Black Trumpet Train Air Horn with 1 Gallon Tank and 150 PSI Compressor Full/Complete Onboard System/Kit VXO8210/4124B Quad Trumpet Train Air Horn Tank Capacity: 1 Gallon (3 liter) 12 volt 150 PSI Compressor Thermal Overload Protection Mounting Hardware Included