B3 Train Horns Complete Kit 150 PSI Onboard Air System w 2 Gallon Tank ReviewbP PP 3 Train Horns Complete Kit 150 PSI Onboard Air System w 2 Gallon Tank PFlat Rack Mount Triple Train Horn w 12 volt electronic solenoid. Overall Horn Dimensions: 19.5" x 17.5" x 5.5". Trumpet Lengths: 16.25", 14", 12".