Find out who's at the door by answering your phone. When a visitor presses the doorbell on the Brass Telephone Entry System Intercom, it sends a distinctive ring to every telephone in your house. This intercom is made of 1/4" solid brass with an AntiqueCopper Finish and the DP Series Design means it has larger overall size at approximately 6" x 4" in comparison to the IU Series which has a single-gang sized finish. It integrates a weather-resistant speaker/microphone with a doorbell button, which can trigger a Telephone Entry Controller to signal you through your phone lines. This system adds safety and convenience to answering the door by allowing you to speak to visitors from any phone in the house before opening your door.# Intercom # Surface mount box # Allen wrench # Mounting screws # Companion board # Instructions