The PM501 provides all basic intercom capabilities plus many of the most advanced features usually only found in more expensive models. Among the best features: Individual output amplifiers for pilot, copilot, and passengers 1 and 2, giving enough audio punch to allow communications in very noisy environments. Voice Operated Relay (VOX) circuitry prevents mic audio from getting through the intercom until someone speaks or triggers the VOX open switch. Automatic fail-safe interconnect to the aircraft radio wires the pilot's headset to the aircraft radio in the event of disrupted power or related failure. Input jack giving pilots and passengers the option to listen to music during flight. During intercom activity, a mute feature will allow communications without distraction. Note that radio reception will NOT mute the music. Pilot isolate mode allows the pilot to communicate without interruption during critical phases of the flight while passengers talk and listen to music. Separate pilot and copilot transmit capabilities ensures that only the person pressing the PTT will be heard over the radio. With the PM501, you get years of trouble-free operation in a very inexpensive unit.