... free calls3.300meters barrier free distance3.5 inch Wireless video door phone (1V1)Product introduction:This system can be used ... adhesive on the wall or door, call sound is clear and loud, equipped with high-definition OV7725 digital camera, easy to install ... desk, coffee table, dining table. Functions: 1.2.4G digital frequency hopping and encryption technology, 200meters barrier free distance,strong ...