Features Specifications:b/w Video door phone(video door phone/bell,intercom system)  B/W Video Door Phone(video door phone/bell,intercom system) Specifications: 1) Dimensions (W x H x D): 220 x 220 x 150mm 2) Four-wire system 3) Power supply: 13.5 V DC  4) Material of outdoor unit: Hard ABS 5) Desktop design  Specifications: 1) 5" CRT display  2) Low power consumption. 3) Intercommunication 4) Electric-controlled unlocking 5) With muilti-function:call in,call out,intercom,monitor 6) LED lumination compensation 7) Water-proof, damage-proof, burgla-proof outdoor unit 8) Unique anti-theft design