The Elvox 6601 series monitors are designed to meet any requirement for Videointercom security. Flush wall mounted optional 6149 back box or R660 Drywall brackets. All monitors feature a crystal clear, hi resolution 4" color LCD monitor, electronic tone signaling. Full duplex conversation, door release, monitor activation, accessory pushbuttons. Brightness and color control. Door release indicator LED can be used to show status of entry doors provided with switch contacts. Other features include private conversation, restricted lock control, twisted pair operation microphone, provides clear duplex conversation.