2-Wire 4" Video Intercom anti-vandal door phone for twin / duplex One Dual Call Button Anti-vandal Outdoor station, Night vision Video camera, hands free audio Outdoor station is fabricated from Stainless Steel with dual backlit name plate Two 4" TFT LCD Color monitor; 12 selectable musical tones for call; Night and Day tone mode setting 12 selectable tones could be assigned to calls from different doors (for more than one outdoor unit) System could be expanded up to 16 Monitors; 4 outdoor station; CCTV cameras; Phone Call forwarder