KERUI M525 Wireless Doorbell System

Features:
*Easy to Install: Just plug the receiver into power socket and attach the waterproof touch doorbell button on door, you don't even necessarily have to make holes or damage anything.
*32 Melody Optional: 32 ringtones included will not let you feel bored, you can select on you like. Avoid the same ring with the neighbors. 4 levels adjustable volume.
*Strong Signal, 150m Long Distance Transmission: Long operating range can be up to 500ft(150m) in open space, great for large house including villas, apartment, offices, shops, warehouses, etc.
*Learn Functions: One transmitter can pair with several(max 30) receivers, and one receiver can pair with several(max 30) transmitters. Customize your doorbell according to your need.
*Doorbell Function/Welcome Alarm/Emergency Alarm All in One. Emergency Alarm: Some inconvenient people can call in an emergency and get help as soon as possible.