Features:
1) Door opening: from monitor and from outdoor
2) Mounting: surface
3) Power supply: from internal
4) Intercom function: 4-wire: yes, 2-wire: no
5) Slave monitor: 4-wire: yes, 2-wire: no
6) Slave handset: 4-wire: yes, 2-wire: no
7) Size of TFT LCD: 5"