A combination of several horn, electrical with different frequences.
NSN 4140-01-327-9470
NSN 5895-01-226-5478
NSN 5895-01-532-4090
NSN 5915-00-411-1301
NSN 5915-01-369-4719
NSN 5975-01-221-2361
NSN 6130-01-384-8248
NSN 6105-01-338-9725
NSN 5855-01-542-9059
NSN 5965-01-025-5129
NSN 6650-01-441-3142
NSN 5996-00-619-1877