Vixen Horns Loud 145dB Single Semi Truck Chrome Trumpet Train Air Horn with Weather Protection Cover 3 Gallon Tank and 200 PSI Compressor Full/Complete Onboard System/Kit VXO8330/1264 Immensely loud Single Semi Truck Train Air Horn with Front Weather Protection Cover Tank Capacity: 3 Gallon (12 liter) 200 PSI Compressor (12 volt) Thermal Overload Protection Mounting Hardware Included