A combination of several horn, electrical with different frequences.
NSN 5925-00-615-1464
NSN 5835-00-905-7165
NSN 6620-00-553-8854
NSN 5985-00-393-4694
NSN 5985-00-926-2593
NSN 6220-00-103-3419
NSN 5915-00-957-4819
NSN 5925-01-130-9072
NSN 5998-00-249-5144
NSN 6135-00-826-4798
NSN 5975-00-013-9291
NSN 5975-00-860-5225