The Katrina 540 features the BRAND NEW, insanely LOUD, Katrina Horns. These horns are going to BLOW YOU AWAY!!! !This air system was designed from the ground up to work amazingly with train horns and it does just that. The Viair 400C can refill the 5 gallon tank from 110 to 150 PSI in just 1 minute and 45 seconds. The air system features everything you'll need to have an extremely loud train horn kit up and running in no time; including, a weatherproof pressure switch with built in relay, all the fittings and air line you'll need, and of course the wire and terminals to get it all hooked up. This complete train horn kit is ridiculously loud!