... price VDP-311+CAM-211-6BVideo intercom system for 6-apartments Advantage :The system include 1outdoor unit +6pcs indoor monitor ,support ... Suitable for : Small apartment building,villa area,can support 6pcs apartments/flatsl How to work :Visitor just need press the button ... a small building,it have one gate and not much apartments ,All the apartment use one outdoor unit which can save ...