... compatible. (3)Dual calling, Surveillance, intercom and remote door unlocking are main functions. (4)Color TFT screen display, ... available, 30 seconds active surveillance, 120 seconds intercom (7)Double Ding-Dong ring or chord melody rings are ... the main engine, speak, observe and open the door 5. High definition image display that reappears the visitor ... size: 222 x 215 x 55(mm) 7. Weight :1.3kg/ 1.1kg