You may also like. Four Trumpet Compact Train Air Horn with 150 PSI 3 Liter Air Compressor UK. 12 Volt 4-Trumpet Train Air Horn Kit with 150 PSI Compressor. Brand New, Never Used, Not Refurbished! Need to make a big noise, but only have a little room? These train horns can fit in almost any vehicle, but deliver the big sound you need. Don’t be fooled by their size – they may be small but they pack a punch that can rival any air horn out there. Easy to fit, glistening chrome finishing and tuned train horn sound; these horns are the complete package. Our specialized compressor kits will make your horns really sing. All of our compressor systems come complete with a 12 volt compressor, air tank, pressure switch and mounting hardware...