Truck parts supply along Rizal Ave. or A. Bonifacio Ave. will surely have this in stock. What kind of vehicle will this be attached to? Some mechanics modify the alternator vaccum assembly for air supply instead of addtional load from a compressor unit. Ordinary plastic pairs are sold for a couple of thousand pesos. The stainless long air horn is around 3-5K. Some compressors are sold separetely ranging from 800-3K.

I have tried those cheapo air horns before, it comes with its own small compressor. Not much of help came when every electrical surge from starting an engine. The compressor usually got stuck and won't blow air. I think I still have that set somewhere in our garage.

HTH