9 Channel Home or Office Wireless Intercom System 4 Station Charcoal No more yelling ! Don't have to keep running back and forth between rooms ! CALL button to call/page all stations at once, one to one or one to all stations communication Quick set up designated station - Press and Hold the Channel Button until you hear a beep tone sounds and Button LED lights Direct CHANNEL buttons plus Stations label for easy access of individual communication, with A/B/C channel group switch to avoid unwanted signals No installation required, FM 462 MHz wireless operation, AC Adapter included