Features:1. 300 meters long distance, adjustable tone can change music, prevent string noise is not wrong, simple installation.2. Receiver composition: Indicator, volume key, muisc selection key3. Distance barrier-free 300 meters penetration, strong penetration performance, receiving distance to the Air-to-Ground linear distance can reach 300 meters, note: the actual received signal visual environment changes, different signals due to obstacles are different4. Easy to install: The transmitter is installed outside the door, the receiver installed in the room can be plugged in, press the button of transmitter, receiver smart flashing light, bell rings.5. Widely used in hotel, home, office buildings, etc.Notice:1. Actual color may be slightly different from the image due to different monitor and light effect. Please allow 1-3cm deviation due to manual measurement.Specification:Working range: 300MMusic selection: 36 ringtonesVolume selection: 4 levels of volume adjustablePower supply:The transmitter uses a 12V23A battery(not included)Receiver: plug-inSize:Transmitter: 77x46x20MMReceiver: 90x56x20MMScope of application: family commercial residential areas, office buildings, hospitals, restaurants, factories and other places