Would like to see who is outside before opening the door? The door is too far, or you are disabled or elderly person and find it difficult to walk all the way every time? Its no longer a problem with high tech video door phone. With this system you can supervise front door situation at any time, take a picture of the person at the door and store it in memory, communicate with hands-free audio and unlock the door remotely. Here are 2 Systems for separate homes with built-in memory for 120 colour images and Touch Screen function in each System. High video quality outdoor unit with Sony CCD Night vision camera has 2 Bell Buttons, allows visitor to contact any system and has possibility to connect additional CCTV cameras to the unit for extra security using distributor(switcher). Both Systems can be expanded up to 5 Indoor Units and use intercom function among all monitors. No additional power required for outdoor unit or electronic door latch (door latch not included). Power supply: DC 15-18v supplied by adaptor. Mounting hardware included in the set. PLEASE CONTACT US for additional Monitors, CCD Cameras, wiring schemes or instructions. THANK YOU more info