◆With this, range of wireless calling system can be 980ft(300m) in doors, 5000ft(1500m) in the open air. ◆Easy to install, stable signal ◆Transmit all calling signals or just transmit registered calling signals ◆Can also select the installation position by itself. ◆Size: 6.0*3.2*1.1 in (153*82*29mm) ◆Use a Power Supply Adapter