Opening the boxes from Hornblasters.com, we checked out the Conductor's Special 540 kit. Included in the kit were four train horns, 5-gallon air tank, Viair 400C compressor, Viair pressure switch, air solenoid, assorted fittings, wiring, and 20 feet of 5/16 air line.
HornBlasters Train Horn Kit Installation - Attention Getter