The ETS PA871 is a balanced analog audio adapter that is screw terminal to RJ45 pins 5 and 4. The ETS PA870 Series of Balanced Analog Audio Adapters is ideal for use in applications that require audio signals to be sent over distances greater than 4 meters. Signals may be sent in either direction. By balancing the audio signal as well as isolating it, signals can be easily sent over 100 meters distance. Perfect for Churches, Theaters, Classrooms, Auditoriums or anywhere you need to send analog audio