SUPER EASY TO INSTALL - Ready to work right out of the wireless doorbell box. Plug the doorbell receiver into a socket and fix the doorbell transmitter on anywhere you want with the included accessories(bottom plate,double-sided adhesive tape and screws). WEATHERPROOF TRANSMITTER - The transmitter is rated IP55 weatherproof and acceptable for outdoor use. The wireless range from the transmitter to the indoor receiver is up to 1000 feet(300m),it adopts advanced wireless transmission technology(FSK+FHSS) to avoid the wireless signal interference from other wireless devices and can go through the doors/walls/floors/and et SMART COMPACT RECEIVER - The doorbell receiver has 35 optional melodies and 5 adjustable volume levels(includes Mute mode). Expandable up to 32 transmitters and unlimited receivers for complete coverage of your property and match different melody with different transmitters to differentiate which one is being detected(Such as the melody for the front door is Doorbell Chime,and for the backyard is Dog Barks) MEMORY FUNCTION - Remember your last settings for the doorbell unit ( such as the different melodies for different transmitters) even if the AC power goes out. No need to reset the unit, it is super convenient to use and it is also a good ideal for any occasion such as house,apartment,office,classroom,warehouse and etc.