1 4 inch video doorphone 2 Video intercom,Night Vision 3 3.6mm Lenz,wide ... China's top brand 4'' Black B/W Hand free Video door phone intercom system 1.B/W Handsfree 4 inch ... vision and wide vision4.Four wire connection5 Visitor calling, video intercom, unlock, monitor.6 With warning function7 with power ... water-proof function etc"Specification: 4'' Black B/W Hand free Video door phone intercom system