JBL 2405 Ultra High Frequency Transducer (c1971)

 

The 2405 is designed for use as the ultra-high frequency driver in a wide-range, multi-element loudspeaker system. It features a unique combination of extended frequency response, high efficiency, and wide dispersion pattern.

Link for PDF: JBL-2405-UHF.pdf 

Also:

Link for: 2405  1979 Data Sheet