Features Specifications:Sell B/W video door phones(door phones,intercom system)  B/W Video Door Phone(door phones,intercom system) Specifications: 1) Dimensions (W x H x D): 186 x 222 x 55mm 2) Four-wire system 3) Power supply: 13.5 V DC / AC 110V~240V 4) Material of outdoor unit: Hard ABS  5) With powersupply built-in door phone  Features: 1) 4" CRT B/W 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