MPC Air Horns for Trucks; Dual Big Rig 25" w/Heavy Duty 12-Volt 150 PSI Compressor Two 25" Truck Horns, 147.3 dB 150 PSI?All-in-one Air System Pressure switch (120 PSI on, 150 PSI off) and air fittings pre-installed Air tube, horn button & mounting hardware included